diff --git a/src/class_diagram/generators/json/class_diagram_generator.cc b/src/class_diagram/generators/json/class_diagram_generator.cc
index 69b00950..464b8772 100644
--- a/src/class_diagram/generators/json/class_diagram_generator.cc
+++ b/src/class_diagram/generators/json/class_diagram_generator.cc
@@ -85,7 +85,7 @@ void to_json(nlohmann::json &j, const class_method &c)
 void to_json(nlohmann::json &j, const class_parent &c)
 {
     j["is_virtual"] = c.is_virtual();
-    j["id"] = std::to_string(c.id());
+    j["id"] = std::to_string(c.id().value());
     if (c.access() != common::model::access_t::kNone)
         j["access"] = to_string(c.access());
     j["name"] = c.name();
@@ -331,7 +331,7 @@ void generator::generate_relationships(
         }
 
         nlohmann::json rel = r;
-        rel["source"] = std::to_string(c.id());
+        rel["source"] = std::to_string(c.id().value());
         parent["relationships"].push_back(rel);
     }
 
@@ -340,7 +340,7 @@ void generator::generate_relationships(
             common::model::relationship r(
                 relationship_t::kExtension, b.id(), b.access());
             nlohmann::json rel = r;
-            rel["source"] = std::to_string(c.id());
+            rel["source"] = std::to_string(c.id().value());
             parent["relationships"].push_back(rel);
         }
     }
@@ -362,7 +362,7 @@ void generator::generate_relationships(
         }
 
         nlohmann::json rel = r;
-        rel["source"] = std::to_string(c.id());
+        rel["source"] = std::to_string(c.id().value());
         parent["relationships"].push_back(rel);
     }
 }
@@ -383,7 +383,7 @@ void generator::generate_relationships(
         }
 
         nlohmann::json rel = r;
-        rel["source"] = std::to_string(c.id());
+        rel["source"] = std::to_string(c.id().value());
         parent["relationships"].push_back(rel);
     }
 }
diff --git a/src/class_diagram/generators/mermaid/class_diagram_generator.cc b/src/class_diagram/generators/mermaid/class_diagram_generator.cc
index 436d60b4..b37c0c0a 100644
--- a/src/class_diagram/generators/mermaid/class_diagram_generator.cc
+++ b/src/class_diagram/generators/mermaid/class_diagram_generator.cc
@@ -405,7 +405,7 @@ void generator::generate_relationships(
         LOG_DBG("== Processing relationship {}", to_string(r.type()));
 
         std::stringstream relstr;
-        clanguml::common::id_t destination{0};
+        clanguml::common::id_t destination{};
         try {
             destination = r.destination();
 
@@ -513,7 +513,7 @@ void generator::generate_relationships(
         LOG_DBG("== Processing relationship {}", to_string(r.type()));
 
         std::stringstream relstr;
-        clanguml::common::id_t destination{0};
+        clanguml::common::id_t destination{};
         try {
             destination = r.destination();
 
@@ -584,7 +584,7 @@ void generator::generate_relationships(const enum_ &e, std::ostream &ostr) const
         if (!model().should_include(r.type()))
             continue;
 
-        clanguml::common::id_t destination{0};
+        clanguml::common::id_t destination{};
         std::stringstream relstr;
         try {
             destination = r.destination();
diff --git a/src/class_diagram/generators/plantuml/class_diagram_generator.cc b/src/class_diagram/generators/plantuml/class_diagram_generator.cc
index 67016667..11bdbc78 100644
--- a/src/class_diagram/generators/plantuml/class_diagram_generator.cc
+++ b/src/class_diagram/generators/plantuml/class_diagram_generator.cc
@@ -488,7 +488,7 @@ void generator::generate_relationships(
             plantuml_common::to_plantuml(r, config()));
 
         std::stringstream relstr;
-        clanguml::common::id_t destination{0};
+        clanguml::common::id_t destination{};
         try {
             destination = r.destination();
 
@@ -583,7 +583,7 @@ void generator::generate_relationships(
         LOG_DBG("== Processing relationship {}", to_string(r.type()));
 
         std::stringstream relstr;
-        clanguml::common::id_t destination{0};
+        clanguml::common::id_t destination{};
         try {
             destination = r.destination();
 
@@ -664,7 +664,7 @@ void generator::generate_relationships(const enum_ &e, std::ostream &ostr) const
         if (!model().should_include(r.type()))
             continue;
 
-        clanguml::common::id_t destination{0};
+        clanguml::common::id_t destination{};
         std::stringstream relstr;
         try {
             destination = r.destination();
diff --git a/src/class_diagram/model/class.h b/src/class_diagram/model/class.h
index b8375aec..5e20990c 100644
--- a/src/class_diagram/model/class.h
+++ b/src/class_diagram/model/class.h
@@ -187,7 +187,7 @@ struct hash<std::reference_wrapper<clanguml::class_diagram::model::class_>> {
     {
         using clanguml::common::id_t;
 
-        return std::hash<id_t>{}(key.get().id());
+        return std::hash<uint64_t>{}(key.get().id().value());
     }
 };
 } // namespace std
diff --git a/src/class_diagram/visitor/translation_unit_visitor.cc b/src/class_diagram/visitor/translation_unit_visitor.cc
index 8431a81a..9dbd3d3e 100644
--- a/src/class_diagram/visitor/translation_unit_visitor.cc
+++ b/src/class_diagram/visitor/translation_unit_visitor.cc
@@ -130,7 +130,7 @@ bool translation_unit_visitor::VisitEnumDecl(clang::EnumDecl *enm)
             clang::dyn_cast<clang::RecordDecl>(parent);
 
         if (parent_record_decl != nullptr) {
-            int64_t local_id = parent_record_decl->getID();
+            common::id_t local_id{parent_record_decl->getID()};
 
             // First check if the parent has been added to the diagram as
             // regular class
@@ -222,8 +222,8 @@ bool translation_unit_visitor::VisitClassTemplateSpecializationDecl(
     if (!template_specialization.template_specialization_found()) {
         // Only do this if we haven't found a better specialization during
         // construction of the template specialization
-        const auto maybe_id =
-            id_mapper().get_global_id(cls->getSpecializedTemplate()->getID());
+        const common::id_t ast_id{cls->getSpecializedTemplate()->getID()};
+        const auto maybe_id = id_mapper().get_global_id(ast_id);
         if (maybe_id.has_value())
             template_specialization.add_relationship(
                 {relationship_t::kInstantiation, maybe_id.value()});
@@ -621,8 +621,8 @@ void translation_unit_visitor::process_concept_specialization_relationships(
         should_include(cpt)) {
 
         const auto cpt_name = cpt->getNameAsString();
-
-        const auto maybe_id = id_mapper().get_global_id(cpt->getID());
+        const common::id_t ast_id{cpt->getID()};
+        const auto maybe_id = id_mapper().get_global_id(ast_id);
         if (!maybe_id)
             return;
 
@@ -707,7 +707,8 @@ bool translation_unit_visitor::VisitCXXRecordDecl(clang::CXXRecordDecl *cls)
     if (cls->isTemplated() && (cls->getDescribedTemplate() != nullptr)) {
         // If the described templated of this class is already in the model
         // skip it:
-        if (id_mapper().get_global_id(cls->getDescribedTemplate()->getID()))
+        const common::id_t ast_id{cls->getDescribedTemplate()->getID()};
+        if (id_mapper().get_global_id(ast_id))
             return true;
     }
 
@@ -878,19 +879,19 @@ void translation_unit_visitor::process_record_parent(
         if (parent_record_decl != nullptr) {
             parent_ns = common::get_tag_namespace(*parent_record_decl);
 
-            int64_t local_id = parent_record_decl->getID();
+            common::id_t ast_id{parent_record_decl->getID()};
 
             // First check if the parent has been added to the diagram as
             // regular class
-            id_opt = id_mapper().get_global_id(local_id);
+            id_opt = id_mapper().get_global_id(ast_id);
 
             // If not, check if the parent template declaration is in the
             // model
             if (!id_opt) {
                 if (parent_record_decl->getDescribedTemplate() != nullptr) {
-                    local_id =
+                    ast_id =
                         parent_record_decl->getDescribedTemplate()->getID();
-                    id_opt = id_mapper().get_global_id(local_id);
+                    id_opt = id_mapper().get_global_id(ast_id);
                 }
             }
         }
@@ -1993,34 +1994,43 @@ void translation_unit_visitor::resolve_local_to_global_ids()
     //       to elements
     for (const auto &cls : diagram().classes()) {
         for (auto &rel : cls.get().relationships()) {
-            const auto maybe_id = id_mapper().get_global_id(rel.destination());
-            if (maybe_id) {
-                LOG_DBG("= Resolved instantiation destination from local "
-                        "id {} to global id {}",
-                    rel.destination(), *maybe_id);
-                rel.set_destination(*maybe_id);
+            if (!rel.destination().is_global()) {
+                const auto maybe_id =
+                    id_mapper().get_global_id(rel.destination());
+                if (maybe_id) {
+                    LOG_DBG("= Resolved instantiation destination from local "
+                            "id {} to global id {}",
+                        rel.destination(), *maybe_id);
+                    rel.set_destination(*maybe_id);
+                }
             }
         }
     }
     for (const auto &cpt : diagram().concepts()) {
         for (auto &rel : cpt.get().relationships()) {
-            const auto maybe_id = id_mapper().get_global_id(rel.destination());
-            if (maybe_id) {
-                LOG_DBG("= Resolved instantiation destination from local "
-                        "id {} to global id {}",
-                    rel.destination(), *maybe_id);
-                rel.set_destination(*maybe_id);
+            if (!rel.destination().is_global()) {
+                const auto maybe_id =
+                    id_mapper().get_global_id(rel.destination());
+                if (maybe_id) {
+                    LOG_DBG("= Resolved instantiation destination from local "
+                            "id {} to global id {}",
+                        rel.destination(), *maybe_id);
+                    rel.set_destination(*maybe_id);
+                }
             }
         }
     }
     for (const auto &enm : diagram().enums()) {
         for (auto &rel : enm.get().relationships()) {
-            const auto maybe_id = id_mapper().get_global_id(rel.destination());
-            if (maybe_id) {
-                LOG_DBG("= Resolved instantiation destination from local "
-                        "id {} to global id {}",
-                    rel.destination(), *maybe_id);
-                rel.set_destination(*maybe_id);
+            if (!rel.destination().is_global()) {
+                const auto maybe_id =
+                    id_mapper().get_global_id(rel.destination());
+                if (maybe_id) {
+                    LOG_DBG("= Resolved instantiation destination from local "
+                            "id {} to global id {}",
+                        rel.destination(), *maybe_id);
+                    rel.set_destination(*maybe_id);
+                }
             }
         }
     }
@@ -2177,7 +2187,7 @@ void translation_unit_visitor::find_instantiation_relationships(
     std::string best_match_full_name{};
     auto full_template_name = template_instantiation.full_name(false);
     int best_match{};
-    common::id_t best_match_id{0};
+    common::id_t best_match_id{};
 
     for (const auto templ : diagram().classes()) {
         if (templ.get() == template_instantiation)
@@ -2196,9 +2206,9 @@ void translation_unit_visitor::find_instantiation_relationships(
     }
 
     auto templated_decl_global_id =
-        id_mapper().get_global_id(templated_decl_id).value_or(0);
+        id_mapper().get_global_id(templated_decl_id).value_or(common::id_t{});
 
-    if (best_match_id > 0) {
+    if (best_match_id.value() > 0) {
         destination = best_match_full_name;
         template_instantiation.add_relationship(
             {common::model::relationship_t::kInstantiation, best_match_id});
diff --git a/src/common/clang_utils.cc b/src/common/clang_utils.cc
index c02ff514..66631685 100644
--- a/src/common/clang_utils.cc
+++ b/src/common/clang_utils.cc
@@ -415,49 +415,49 @@ bool is_subexpr_of(const clang::Stmt *parent_stmt, const clang::Stmt *sub_stmt)
         [sub_stmt](const auto *e) { return is_subexpr_of(e, sub_stmt); });
 }
 
-template <> id_t to_id(const std::string &full_name)
+template <> common::id_t to_id(const std::string &full_name)
 {
-    return static_cast<id_t>(std::hash<std::string>{}(full_name) >> 3U);
+    return static_cast<common::id_t>(std::hash<std::string>{}(full_name));
 }
 
-id_t to_id(const clang::QualType &type, const clang::ASTContext &ctx)
+common::id_t to_id(const clang::QualType &type, const clang::ASTContext &ctx)
 {
     return to_id(common::to_string(type, ctx));
 }
 
-template <> id_t to_id(const clang::NamespaceDecl &declaration)
+template <> common::id_t to_id(const clang::NamespaceDecl &declaration)
 {
     return to_id(get_qualified_name(declaration));
 }
 
-template <> id_t to_id(const clang::RecordDecl &declaration)
+template <> common::id_t to_id(const clang::RecordDecl &declaration)
 {
     return to_id(get_qualified_name(declaration));
 }
 
-template <> id_t to_id(const clang::EnumDecl &declaration)
+template <> common::id_t to_id(const clang::EnumDecl &declaration)
 {
     return to_id(get_qualified_name(declaration));
 }
 
-template <> id_t to_id(const clang::TagDecl &declaration)
+template <> common::id_t to_id(const clang::TagDecl &declaration)
 {
     return to_id(get_qualified_name(declaration));
 }
 
-template <> id_t to_id(const clang::CXXRecordDecl &declaration)
+template <> common::id_t to_id(const clang::CXXRecordDecl &declaration)
 {
     return to_id(get_qualified_name(declaration));
 }
 
-template <> id_t to_id(const clang::EnumType &t) { return to_id(*t.getDecl()); }
+template <> common::id_t to_id(const clang::EnumType &t) { return to_id(*t.getDecl()); }
 
-template <> id_t to_id(const std::filesystem::path &file)
+template <> common::id_t to_id(const std::filesystem::path &file)
 {
     return to_id(file.lexically_normal().string());
 }
 
-template <> id_t to_id(const clang::TemplateArgument &template_argument)
+template <> common::id_t to_id(const clang::TemplateArgument &template_argument)
 {
     if (template_argument.getKind() == clang::TemplateArgument::Type) {
         if (const auto *enum_type =
diff --git a/src/common/clang_utils.h b/src/common/clang_utils.h
index 25be8986..80f4c7db 100644
--- a/src/common/clang_utils.h
+++ b/src/common/clang_utils.h
@@ -178,27 +178,27 @@ bool is_subexpr_of(const clang::Stmt *parent_stmt, const clang::Stmt *sub_stmt);
  *
  * @{
  */
-template <typename T> id_t to_id(const T &declaration);
+template <typename T> common::id_t to_id(const T &declaration);
 
-template <> id_t to_id(const std::string &full_name);
+template <> common::id_t to_id(const std::string &full_name);
 
-id_t to_id(const clang::QualType &type, const clang::ASTContext &ctx);
+common::id_t to_id(const clang::QualType &type, const clang::ASTContext &ctx);
 
-template <> id_t to_id(const clang::NamespaceDecl &declaration);
+template <> common::id_t to_id(const clang::NamespaceDecl &declaration);
 
-template <> id_t to_id(const clang::CXXRecordDecl &declaration);
+template <> common::id_t to_id(const clang::CXXRecordDecl &declaration);
 
-template <> id_t to_id(const clang::RecordDecl &declaration);
+template <> common::id_t to_id(const clang::RecordDecl &declaration);
 
-template <> id_t to_id(const clang::EnumDecl &declaration);
+template <> common::id_t to_id(const clang::EnumDecl &declaration);
 
-template <> id_t to_id(const clang::TagDecl &declaration);
+template <> common::id_t to_id(const clang::TagDecl &declaration);
 
-template <> id_t to_id(const clang::EnumType &type);
+template <> common::id_t to_id(const clang::EnumType &type);
 
-template <> id_t to_id(const clang::TemplateSpecializationType &type);
+template <> common::id_t to_id(const clang::TemplateSpecializationType &type);
 
-template <> id_t to_id(const std::filesystem::path &type);
+template <> common::id_t to_id(const std::filesystem::path &type);
 /** @} */ // end of to_id
 
 /**
diff --git a/src/common/generators/json/generator.cc b/src/common/generators/json/generator.cc
index 79622391..aec3cd27 100644
--- a/src/common/generators/json/generator.cc
+++ b/src/common/generators/json/generator.cc
@@ -31,7 +31,7 @@ void to_json(nlohmann::json &j, const source_location &sl)
 
 void to_json(nlohmann::json &j, const element &c)
 {
-    j = json{{"id", std::to_string(c.id())},
+    j = json{{"id", std::to_string(c.id().value())},
         {"name", common::generators::json::render_name(c.name())},
         {"namespace", c.get_namespace().to_string()}, {"type", c.type_name()},
         {"display_name",
@@ -62,7 +62,7 @@ void to_json(nlohmann::json &j, const template_parameter &c)
 void to_json(nlohmann::json &j, const relationship &c)
 {
     j["type"] = to_string(c.type());
-    j["destination"] = std::to_string(c.destination());
+    j["destination"] = std::to_string(c.destination().value());
     if (!c.multiplicity_source().empty())
         j["multiplicity_source"] = c.multiplicity_source();
     if (!c.multiplicity_destination().empty())
diff --git a/src/common/model/diagram_element.cc b/src/common/model/diagram_element.cc
index 8e307fc0..97ab0ff4 100644
--- a/src/common/model/diagram_element.cc
+++ b/src/common/model/diagram_element.cc
@@ -26,7 +26,7 @@ namespace clanguml::common::model {
 
 diagram_element::diagram_element() = default;
 
-common::id_t diagram_element::id() const { return id_; }
+const common::id_t & diagram_element::id() const { return id_; }
 
 void diagram_element::set_id(common::id_t id) { id_ = id; }
 
@@ -42,9 +42,9 @@ void diagram_element::set_parent_element_id(common::id_t id)
 
 std::string diagram_element::alias() const
 {
-    assert(id_ >= 0);
+    assert(id_.value() >= 0);
 
-    return fmt::format("C_{:022}", id_);
+    return fmt::format("C_{:022}", id_.value());
 }
 
 void diagram_element::add_relationship(relationship &&cr)
diff --git a/src/common/model/diagram_element.h b/src/common/model/diagram_element.h
index 224181af..3074dffe 100644
--- a/src/common/model/diagram_element.h
+++ b/src/common/model/diagram_element.h
@@ -53,7 +53,7 @@ public:
      *
      * @return Elements id.
      */
-    common::id_t id() const;
+    const common::id_t& id() const;
 
     /**
      * Set elements id.
@@ -185,8 +185,8 @@ public:
     void complete(bool completed);
 
 private:
-    id_t id_{0};
-    std::optional<id_t> parent_element_id_{0};
+    id_t id_{};
+    std::optional<common::id_t> parent_element_id_{};
     std::string name_;
     std::vector<relationship> relationships_;
     bool nested_{false};
diff --git a/src/common/model/diagram_filter.h b/src/common/model/diagram_filter.h
index 6e86e0e6..2176e13a 100644
--- a/src/common/model/diagram_filter.h
+++ b/src/common/model/diagram_filter.h
@@ -55,7 +55,8 @@ template <typename ElementT, typename DiagramT>
 const clanguml::common::optional_ref<ElementT> get(
     const DiagramT &d, const std::string &full_name);
 
-template <typename ElementT> int64_t destination_comparator(const ElementT &e)
+template <typename ElementT>
+common::id_t destination_comparator(const ElementT &e)
 {
     return e.id();
 }
diff --git a/src/common/model/package.h b/src/common/model/package.h
index 353b5cf1..981ad5ae 100644
--- a/src/common/model/package.h
+++ b/src/common/model/package.h
@@ -91,7 +91,7 @@ struct hash<std::reference_wrapper<clanguml::common::model::package>> {
     {
         using clanguml::common::id_t;
 
-        return std::hash<id_t>{}(key.get().id());
+        return std::hash<id_t::type>{}(key.get().id().value());
     }
 };
 } // namespace std
\ No newline at end of file
diff --git a/src/common/model/relationship.cc b/src/common/model/relationship.cc
index 00800c5d..fa02676e 100644
--- a/src/common/model/relationship.cc
+++ b/src/common/model/relationship.cc
@@ -22,7 +22,7 @@
 
 namespace clanguml::common::model {
 
-relationship::relationship(relationship_t type, int64_t destination,
+relationship::relationship(relationship_t type, common::id_t destination,
     access_t access, std::string label, std::string multiplicity_source,
     std::string multiplicity_destination)
     : type_{type}
@@ -38,7 +38,7 @@ void relationship::set_type(relationship_t type) noexcept { type_ = type; }
 
 relationship_t relationship::type() const noexcept { return type_; }
 
-void relationship::set_destination(int64_t destination)
+void relationship::set_destination(common::id_t destination)
 {
     destination_ = destination;
 }
diff --git a/src/common/model/relationship.h b/src/common/model/relationship.h
index db282908..400ff663 100644
--- a/src/common/model/relationship.h
+++ b/src/common/model/relationship.h
@@ -74,14 +74,14 @@ public:
      *
      * @param destination Target element id.
      */
-    void set_destination(int64_t destination);
+    void set_destination(common::id_t destination);
 
     /**
      * Get the id of the target element of this relationship.
      *
      * @return Target element id.
      */
-    clanguml::common::id_t destination() const;
+    common::id_t destination() const;
 
     /**
      * Set the relationship multiplicity at the source.
diff --git a/src/common/model/source_file.h b/src/common/model/source_file.h
index 24cf26d5..46007d72 100644
--- a/src/common/model/source_file.h
+++ b/src/common/model/source_file.h
@@ -212,7 +212,7 @@ struct hash<std::reference_wrapper<clanguml::common::model::source_file>> {
     {
         using clanguml::common::id_t;
 
-        return std::hash<id_t>{}(key.get().id());
+        return std::hash<id_t::type>{}(key.get().id().value());
     }
 };
 } // namespace std
\ No newline at end of file
diff --git a/src/common/model/template_parameter.cc b/src/common/model/template_parameter.cc
index b31270d9..c66b40b3 100644
--- a/src/common/model/template_parameter.cc
+++ b/src/common/model/template_parameter.cc
@@ -505,7 +505,7 @@ std::string template_parameter::to_string(
 }
 
 bool template_parameter::find_nested_relationships(
-    std::vector<std::pair<int64_t, common::model::relationship_t>>
+    std::vector<std::pair<common::id_t, common::model::relationship_t>>
         &nested_relationships,
     common::model::relationship_t hint,
     const std::function<bool(const std::string &full_name)> &should_include)
diff --git a/src/common/model/template_parameter.h b/src/common/model/template_parameter.h
index c9d0aecc..27f5270f 100644
--- a/src/common/model/template_parameter.h
+++ b/src/common/model/template_parameter.h
@@ -19,6 +19,7 @@
 
 #include "common/model/enums.h"
 #include "common/model/namespace.h"
+#include "common/types.h"
 
 #include <deque>
 #include <optional>
@@ -165,14 +166,14 @@ public:
      *
      * @param id Id of parameter
      */
-    void set_id(const int64_t id) { id_ = id; }
+    void set_id(const common::id_t &id) { id_ = id; }
 
     /**
      * Get id of the template parameter
      *
      * @return Id of the template parameter
      */
-    const std::optional<int64_t> &id() const { return id_; }
+    const std::optional<common::id_t> &id() const { return id_; }
 
     /**
      * Set the name of the template parameter
@@ -388,7 +389,7 @@ public:
      * @return
      */
     bool find_nested_relationships(
-        std::vector<std::pair<int64_t, common::model::relationship_t>>
+        std::vector<std::pair<common::id_t, common::model::relationship_t>>
             &nested_relationships,
         common::model::relationship_t hint,
         const std::function<bool(const std::string &full_name)> &should_include)
@@ -532,7 +533,7 @@ private:
      */
     std::vector<template_parameter> template_params_;
 
-    std::optional<int64_t> id_;
+    std::optional<common::id_t> id_;
 
     bool is_unexposed_{false};
 };
diff --git a/src/common/types.h b/src/common/types.h
index 7da7ea74..d1c3fa64 100644
--- a/src/common/types.h
+++ b/src/common/types.h
@@ -29,7 +29,87 @@
 
 namespace clanguml::common {
 
-using id_t = int64_t;
+class id_t {
+public:
+    using type = uint64_t;
+
+    id_t()
+        : value_{0ULL}
+        , is_global_{true}
+    {
+    }
+
+    explicit id_t(int64_t id)
+        : value_{static_cast<type>(id)}
+        , is_global_{false}
+    {
+    }
+
+    explicit id_t(type id)
+        : value_{id}
+        , is_global_{true}
+    {
+    }
+
+    id_t(const id_t &) = default;
+    id_t(id_t &&) noexcept = default;
+    id_t &operator=(const id_t &) = default;
+    id_t &operator=(id_t &&) noexcept = default;
+
+    id_t &operator=(int64_t ast_id)
+    {
+        assert(!is_global_);
+        value_ = static_cast<uint64_t>(ast_id);
+        return *this;
+    }
+
+    ~id_t() = default;
+
+    bool is_global() const { return is_global_; }
+
+    friend bool operator==(const id_t &lhs, const id_t &rhs)
+    {
+        return (lhs.is_global_ == rhs.is_global_) && (lhs.value_ == rhs.value_);
+    }
+
+    friend bool operator==(const id_t &lhs, const uint64_t &v)
+    {
+        return lhs.value_ == v;
+    }
+
+    friend bool operator!=(const id_t &lhs, const uint64_t &v)
+    {
+        return lhs.value_ != v;
+    }
+
+    friend bool operator!=(const id_t &lhs, const id_t &rhs)
+    {
+        return !(lhs == rhs);
+    }
+
+    friend bool operator<(const id_t &lhs, const id_t &rhs)
+    {
+        if (lhs.is_global_ != rhs.is_global_) {
+            return lhs.value_ < rhs.value_ + 1;
+        }
+
+        return lhs.value_ <
+            rhs.value_; // Compare values if is_global_ are the same
+    }
+
+    type value() const { return value_; }
+
+    int64_t ast_local_value() const
+    {
+        assert(!is_global_);
+
+        return static_cast<int64_t>(value_);
+    }
+
+private:
+    type value_;
+    bool is_global_;
+};
 
 /**
  * Type of output diagram format generator.
@@ -292,4 +372,14 @@ using namespace_or_regex = common::or_regex<common::model::namespace_>;
 
 struct path_or_regex : public or_regex<std::filesystem::path> { };
 
-} // namespace clanguml::common
\ No newline at end of file
+} // namespace clanguml::common
+
+template <> class fmt::formatter<clanguml::common::id_t> {
+public:
+    constexpr auto parse(format_parse_context &ctx) { return ctx.begin(); }
+    template <typename Context>
+    constexpr auto format(clanguml::common::id_t const &id, Context &ctx) const
+    {
+        return format_to(ctx.out(), "{}", id.value());
+    }
+};
\ No newline at end of file
diff --git a/src/common/visitor/ast_id_mapper.cc b/src/common/visitor/ast_id_mapper.cc
index b9d22787..6083d429 100644
--- a/src/common/visitor/ast_id_mapper.cc
+++ b/src/common/visitor/ast_id_mapper.cc
@@ -25,12 +25,17 @@ void ast_id_mapper::add(int64_t ast_id, id_t global_id)
     id_map_.emplace(ast_id, global_id);
 }
 
-std::optional<id_t> ast_id_mapper::get_global_id(int64_t ast_id)
+std::optional<id_t> ast_id_mapper::get_global_id(common::id_t ast_id)
 {
-    if (id_map_.count(ast_id) == 0)
+    assert(!ast_id.is_global());
+
+    if (ast_id.is_global())
         return {};
 
-    return id_map_.at(ast_id);
+    if (id_map_.count(ast_id.ast_local_value()) == 0)
+        return {};
+
+    return id_map_.at(ast_id.ast_local_value());
 }
 
 } // namespace clanguml::common::visitor
\ No newline at end of file
diff --git a/src/common/visitor/ast_id_mapper.h b/src/common/visitor/ast_id_mapper.h
index 87a7ef42..5951c9c5 100644
--- a/src/common/visitor/ast_id_mapper.h
+++ b/src/common/visitor/ast_id_mapper.h
@@ -58,7 +58,7 @@ public:
      * @param ast_id Clang's local AST id.
      * @return Global id, if exists.
      */
-    std::optional<id_t> get_global_id(int64_t ast_id);
+    std::optional<id_t> get_global_id(common::id_t ast_id);
 
 private:
     std::map</* Clang AST translation unit local id */ int64_t,
diff --git a/src/common/visitor/template_builder.h b/src/common/visitor/template_builder.h
index 7a446e23..d68afbd2 100644
--- a/src/common/visitor/template_builder.h
+++ b/src/common/visitor/template_builder.h
@@ -661,8 +661,8 @@ void template_builder<VisitorT>::build_from_template_declaration(
                                 templated_element.value().add_relationship(
                                     {relationship_t::kConstraint,
                                         id_mapper()
-                                            .get_global_id(
-                                                named_concept->getID())
+                                            .get_global_id(common::id_t{
+                                                named_concept->getID()})
                                             .value(),
                                         model::access_t::kNone,
                                         ct.name().value()});
@@ -865,7 +865,8 @@ void template_builder<VisitorT>::build(
     if constexpr (std::is_same_v<typename VisitorT::diagram_t,
                       class_diagram::model::diagram>) {
         find_instantiation_relationships(template_instantiation,
-            template_decl->getID(), full_template_specialization_name);
+            common::id_t{template_decl->getID()},
+            full_template_specialization_name);
     }
 
     template_instantiation.set_id(
@@ -910,7 +911,7 @@ void template_builder<VisitorT>::build_from_class_template_specialization(
     if constexpr (std::is_same_v<typename VisitorT::diagram_t,
                       class_diagram::model::diagram>) {
         find_instantiation_relationships(template_instantiation,
-            template_specialization.getID(), qualified_name);
+            common::id_t{template_specialization.getID()}, qualified_name);
     }
 
     visitor_.set_source_location(*template_decl, template_instantiation);
diff --git a/src/include_diagram/generators/json/include_diagram_generator.cc b/src/include_diagram/generators/json/include_diagram_generator.cc
index a1c6853b..4a2c934c 100644
--- a/src/include_diagram/generators/json/include_diagram_generator.cc
+++ b/src/include_diagram/generators/json/include_diagram_generator.cc
@@ -44,7 +44,7 @@ void generator::generate_relationships(
             [this](const auto &r) { return model().should_include(r.type()); },
             [&f, &parent](const auto &r) {
                 nlohmann::json rel = r;
-                rel["source"] = std::to_string(f.id());
+                rel["source"] = std::to_string(f.id().value());
                 parent["relationships"].push_back(std::move(rel));
             });
     }
@@ -53,7 +53,7 @@ void generator::generate_relationships(
 void generator::generate(const source_file &f, nlohmann::json &parent) const
 {
     nlohmann::json j;
-    j["id"] = std::to_string(f.id());
+    j["id"] = std::to_string(f.id().value());
     j["name"] = f.name();
     auto display_name = f.full_name(false);
 #if defined(_MSC_VER)
diff --git a/src/include_diagram/model/diagram.cc b/src/include_diagram/model/diagram.cc
index 0b385581..72275351 100644
--- a/src/include_diagram/model/diagram.cc
+++ b/src/include_diagram/model/diagram.cc
@@ -51,7 +51,7 @@ void diagram::add_file(std::unique_ptr<common::model::source_file> &&f)
     auto &ff = *f;
 
     assert(!ff.name().empty());
-    assert(ff.id() != 0);
+    assert(ff.id().value() != 0);
 
     element_view<source_file>::add(ff);
 
diff --git a/src/package_diagram/generators/json/package_diagram_generator.cc b/src/package_diagram/generators/json/package_diagram_generator.cc
index 7fffd3dd..6cd001e6 100644
--- a/src/package_diagram/generators/json/package_diagram_generator.cc
+++ b/src/package_diagram/generators/json/package_diagram_generator.cc
@@ -44,7 +44,7 @@ void generator::generate_relationships(
                     dynamic_cast<const package &>(*destination_package)))
                 continue;
 
-            rel["source"] = std::to_string(p.id());
+            rel["source"] = std::to_string(p.id().value());
             parent["relationships"].push_back(std::move(rel));
         }
     }
@@ -63,7 +63,7 @@ void generator::generate(const package &p, nlohmann::json &parent) const
     const auto &uns = config().using_namespace();
     if (!uns.starts_with({p.full_name(false)})) {
         nlohmann::json j;
-        j["id"] = std::to_string(p.id());
+        j["id"] = std::to_string(p.id().value());
         j["name"] = p.name();
         j["type"] = to_string(config().package_type());
         j["display_name"] = p.name();
diff --git a/src/package_diagram/visitor/translation_unit_visitor.cc b/src/package_diagram/visitor/translation_unit_visitor.cc
index 850e1aec..fcfcdb21 100644
--- a/src/package_diagram/visitor/translation_unit_visitor.cc
+++ b/src/package_diagram/visitor/translation_unit_visitor.cc
@@ -78,7 +78,7 @@ bool translation_unit_visitor::VisitNamespaceDecl(clang::NamespaceDecl *ns)
     p->set_id(common::to_id(*ns));
     set_source_location(*ns, *p);
 
-    assert(p->id() > 0);
+    assert(p->id().value() > 0);
 
     if (diagram().should_include(*p) && !diagram().get(p->id())) {
         process_comment(*ns, *p);
@@ -282,7 +282,7 @@ void translation_unit_visitor::add_relationships(
 
     auto current_package_id = get_package_id(cls);
 
-    if (current_package_id == 0)
+    if (current_package_id.value() == 0)
         // These are relationships to a global namespace, and we don't care
         // about those
         return;
diff --git a/src/sequence_diagram/generators/json/sequence_diagram_generator.cc b/src/sequence_diagram/generators/json/sequence_diagram_generator.cc
index ad2b206d..e62b873c 100644
--- a/src/sequence_diagram/generators/json/sequence_diagram_generator.cc
+++ b/src/sequence_diagram/generators/json/sequence_diagram_generator.cc
@@ -53,7 +53,7 @@ void to_json(nlohmann::json &j, const participant &c)
 
 void to_json(nlohmann::json &j, const activity &c)
 {
-    j["participant_id"] = std::to_string(c.from());
+    j["participant_id"] = std::to_string(c.from().value());
 }
 
 } // namespace clanguml::sequence_diagram::model
@@ -115,8 +115,8 @@ void generator::generate_call(const message &m, nlohmann::json &parent) const
 
     msg["name"] = message;
     msg["type"] = "message";
-    msg["from"]["activity_id"] = std::to_string(from.value().id());
-    msg["to"]["activity_id"] = std::to_string(to.value().id());
+    msg["from"]["activity_id"] = std::to_string(from.value().id().value());
+    msg["to"]["activity_id"] = std::to_string(to.value().id().value());
     if (const auto &cmt = m.comment(); cmt.has_value())
         msg["comment"] = cmt.value();
 
@@ -125,7 +125,7 @@ void generator::generate_call(const message &m, nlohmann::json &parent) const
             model().get_participant<model::method>(from.value().id()).value();
 
         msg["from"]["participant_id"] =
-            std::to_string(class_participant.class_id());
+            std::to_string(class_participant.class_id().value());
     }
     else if (from.value().type_name() == "function" ||
         from.value().type_name() == "function_template") {
@@ -134,15 +134,17 @@ void generator::generate_call(const message &m, nlohmann::json &parent) const
                 model()
                     .get_participant<model::function>(from.value().id())
                     .value();
-            msg["from"]["participant_id"] =
-                std::to_string(common::to_id(file_participant.file_relative()));
+            msg["from"]["participant_id"] = std::to_string(
+                common::to_id(file_participant.file_relative()).value());
         }
         else {
-            msg["from"]["participant_id"] = std::to_string(from.value().id());
+            msg["from"]["participant_id"] =
+                std::to_string(from.value().id().value());
         }
     }
     else if (from.value().type_name() == "lambda") {
-        msg["from"]["participant_id"] = std::to_string(from.value().id());
+        msg["from"]["participant_id"] =
+            std::to_string(from.value().id().value());
     }
 
     if (to.value().type_name() == "method") {
@@ -150,7 +152,7 @@ void generator::generate_call(const message &m, nlohmann::json &parent) const
             model().get_participant<model::method>(to.value().id()).value();
 
         msg["to"]["participant_id"] =
-            std::to_string(class_participant.class_id());
+            std::to_string(class_participant.class_id().value());
     }
     else if (to.value().type_name() == "function" ||
         to.value().type_name() == "function_template") {
@@ -159,15 +161,16 @@ void generator::generate_call(const message &m, nlohmann::json &parent) const
                 model()
                     .get_participant<model::function>(to.value().id())
                     .value();
-            msg["to"]["participant_id"] =
-                std::to_string(common::to_id(file_participant.file_relative()));
+            msg["to"]["participant_id"] = std::to_string(
+                common::to_id(file_participant.file_relative()).value());
         }
         else {
-            msg["to"]["participant_id"] = std::to_string(to.value().id());
+            msg["to"]["participant_id"] =
+                std::to_string(to.value().id().value());
         }
     }
     else if (to.value().type_name() == "lambda") {
-        msg["to"]["participant_id"] = std::to_string(to.value().id());
+        msg["to"]["participant_id"] = std::to_string(to.value().id().value());
     }
 
     msg["source_location"] =
@@ -299,7 +302,7 @@ void generator::process_while_message(const message &m) const
     nlohmann::json while_block;
     while_block["type"] = "loop";
     while_block["name"] = "while";
-    while_block["activity_id"] = std::to_string(m.from());
+    while_block["activity_id"] = std::to_string(m.from().value());
     if (auto text = m.condition_text(); text.has_value())
         while_block["condition_text"] = *text;
 
@@ -320,7 +323,7 @@ void generator::process_for_message(const message &m) const
     nlohmann::json for_block;
     for_block["type"] = "loop";
     for_block["name"] = "for";
-    for_block["activity_id"] = std::to_string(m.from());
+    for_block["activity_id"] = std::to_string(m.from().value());
     if (auto text = m.condition_text(); text.has_value())
         for_block["condition_text"] = *text;
 
@@ -341,7 +344,7 @@ void generator::process_do_message(const message &m) const
     nlohmann::json do_block;
     do_block["type"] = "loop";
     do_block["name"] = "do";
-    do_block["activity_id"] = std::to_string(m.from());
+    do_block["activity_id"] = std::to_string(m.from().value());
     if (auto text = m.condition_text(); text.has_value())
         do_block["condition_text"] = *text;
 
@@ -362,7 +365,7 @@ void generator::process_try_message(const message &m) const
     nlohmann::json try_block;
     try_block["type"] = "break";
     try_block["name"] = "try";
-    try_block["activity_id"] = std::to_string(m.from());
+    try_block["activity_id"] = std::to_string(m.from().value());
 
     current_block_statement()["messages"].push_back(std::move(try_block));
 
@@ -404,7 +407,7 @@ void generator::process_switch_message(const message &m) const
     nlohmann::json if_block;
     if_block["type"] = "alt";
     if_block["name"] = "switch";
-    if_block["activity_id"] = std::to_string(m.from());
+    if_block["activity_id"] = std::to_string(m.from().value());
 
     current_block_statement()["messages"].push_back(std::move(if_block));
 
@@ -439,7 +442,7 @@ void generator::process_conditional_message(const message &m) const
     nlohmann::json if_block;
     if_block["type"] = "alt";
     if_block["name"] = "conditional";
-    if_block["activity_id"] = std::to_string(m.from());
+    if_block["activity_id"] = std::to_string(m.from().value());
     if (auto text = m.condition_text(); text.has_value())
         if_block["condition_text"] = *text;
 
@@ -507,7 +510,7 @@ void generator::process_if_message(const message &m) const
     nlohmann::json if_block;
     if_block["type"] = "alt";
     if_block["name"] = "if";
-    if_block["activity_id"] = std::to_string(m.from());
+    if_block["activity_id"] = std::to_string(m.from().value());
     if (auto text = m.condition_text(); text.has_value())
         if_block["condition_text"] = *text;
 
@@ -538,10 +541,10 @@ void generator::generate_participant(
     generate_participant(parent, p.value().id(), true);
 }
 
-common::id_t generator::generate_participant(
+std::optional<common::id_t> generator::generate_participant(
     nlohmann::json & /*parent*/, common::id_t id, bool force) const
 {
-    common::id_t participant_id{0};
+    std::optional<common::id_t> participant_id{};
 
     if (!force) {
         for (const auto pid : model().active_participants()) {
@@ -554,27 +557,27 @@ common::id_t generator::generate_participant(
     else
         participant_id = id;
 
-    if (participant_id == 0)
+    if (!participant_id.has_value())
         return participant_id;
 
-    if (is_participant_generated(participant_id))
+    if (is_participant_generated(*participant_id))
         return participant_id;
 
     const auto &participant =
-        model().get_participant<model::participant>(participant_id).value();
+        model().get_participant<model::participant>(*participant_id).value();
 
     const auto participant_type = participant.type_name();
 
     if (participant_type == "method") {
         auto class_participant_id =
             model()
-                .get_participant<model::method>(participant_id)
+                .get_participant<model::method>(*participant_id)
                 .value()
                 .class_id();
 
         LOG_DBG("Generating JSON method participant: {}",
             model()
-                .get_participant<model::method>(participant_id)
+                .get_participant<model::method>(*participant_id)
                 .value()
                 .full_name(false));
 
@@ -584,7 +587,7 @@ common::id_t generator::generate_participant(
                     .get_participant<model::participant>(class_participant_id)
                     .value();
 
-            generated_participants_.emplace(participant_id);
+            generated_participants_.emplace(*participant_id);
             generated_participants_.emplace(class_participant_id);
 
             json_["participants"].push_back(class_participant);
@@ -600,10 +603,11 @@ common::id_t generator::generate_participant(
             return class_participant_id;
         }
 
-        if (!is_participant_generated(participant_id)) {
+        if (!is_participant_generated(*participant_id)) {
             for (auto &p : json_["participants"]) {
-                if (p.at("id") == std::to_string(class_participant_id)) {
-                    generated_participants_.emplace(participant_id);
+                if (p.at("id") ==
+                    std::to_string(class_participant_id.value())) {
+                    generated_participants_.emplace(*participant_id);
                     p["activities"].push_back(participant);
                     return class_participant_id;
                 }
@@ -617,7 +621,7 @@ common::id_t generator::generate_participant(
         // single file
         // participant_id will become activity_id within a file participant
         const auto &function_participant =
-            model().get_participant<model::function>(participant_id).value();
+            model().get_participant<model::function>(*participant_id).value();
 
         const auto file_participant_id =
             common::to_id(function_participant.file_relative());
@@ -634,11 +638,11 @@ common::id_t generator::generate_participant(
             if (is_participant_generated(file_participant_id))
                 return participant_id;
 
-            p["id"] = std::to_string(file_participant_id);
+            p["id"] = std::to_string(file_participant_id.value());
             p["type"] = "file";
             p.erase("source_location");
 
-            generated_participants_.emplace(participant_id);
+            generated_participants_.emplace(participant_id.value());
 
             p["activities"].push_back(participant);
             json_["participants"].push_back(p);
@@ -648,10 +652,10 @@ common::id_t generator::generate_participant(
             return file_participant_id;
         }
 
-        if (!is_participant_generated(participant_id)) {
+        if (!is_participant_generated(*participant_id)) {
             for (auto &p : json_["participants"]) {
-                if (p.at("id") == std::to_string(file_participant_id)) {
-                    generated_participants_.emplace(participant_id);
+                if (p.at("id") == std::to_string(file_participant_id.value())) {
+                    generated_participants_.emplace(*participant_id);
                     p["activities"].push_back(participant);
                 }
             }
@@ -663,7 +667,7 @@ common::id_t generator::generate_participant(
         json_["participants"].push_back(participant);
     }
 
-    generated_participants_.emplace(participant_id);
+    generated_participants_.emplace(*participant_id);
 
     return participant_id;
 }
@@ -700,17 +704,19 @@ void generator::generate_diagram(nlohmann::json &parent) const
         auto from_activity_id = model().get_from_activity_id(from_location);
         auto to_activity_id = model().get_to_activity_id(to_location);
 
-        if (from_activity_id == 0 || to_activity_id == 0)
+        if (!from_activity_id || !to_activity_id)
             continue;
 
         auto message_chains_unique = model().get_all_from_to_message_chains(
-            from_activity_id, to_activity_id);
+            *from_activity_id, *to_activity_id);
 
         nlohmann::json sequence;
         sequence["from_to"]["from"]["location"] = from_location.location;
-        sequence["from_to"]["from"]["id"] = from_activity_id;
+        sequence["from_to"]["from"]["id"] =
+            std::to_string(from_activity_id.value().value());
         sequence["from_to"]["to"]["location"] = to_location.location;
-        sequence["from_to"]["to"]["id"] = to_activity_id;
+        sequence["from_to"]["to"]["id"] =
+            std::to_string(to_activity_id.value().value());
 
         block_statements_stack_.push_back(std::ref(sequence));
 
@@ -742,11 +748,11 @@ void generator::generate_diagram(nlohmann::json &parent) const
             continue;
 
         auto message_chains_unique =
-            model().get_all_from_to_message_chains(0, to_activity_id);
+            model().get_all_from_to_message_chains(common::id_t{}, *to_activity_id);
 
         nlohmann::json sequence;
         sequence["to"]["location"] = to_location.location;
-        sequence["to"]["id"] = to_activity_id;
+        sequence["to"]["id"] = std::to_string(to_activity_id.value().value());
 
         block_statements_stack_.push_back(std::ref(sequence));
 
@@ -773,7 +779,7 @@ void generator::generate_diagram(nlohmann::json &parent) const
 
     for (const auto &sf : config().from()) {
         if (sf.location_type == location_t::function) {
-            common::id_t start_from{0};
+            common::id_t start_from{};
             std::string start_from_str;
             for (const auto &[k, v] : model().sequences()) {
                 const auto &caller = *model().participants().at(v.from());
@@ -812,7 +818,7 @@ void generator::generate_diagram(nlohmann::json &parent) const
 
             nlohmann::json sequence;
             sequence["start_from"]["location"] = sf.location;
-            sequence["start_from"]["id"] = start_from;
+            sequence["start_from"]["id"] = std::to_string(start_from.value());
 
             block_statements_stack_.push_back(std::ref(sequence));
 
diff --git a/src/sequence_diagram/generators/json/sequence_diagram_generator.h b/src/sequence_diagram/generators/json/sequence_diagram_generator.h
index e519f1bb..0eac7e7b 100644
--- a/src/sequence_diagram/generators/json/sequence_diagram_generator.h
+++ b/src/sequence_diagram/generators/json/sequence_diagram_generator.h
@@ -77,7 +77,7 @@ public:
      *              the set of active participants
      * @return Id of the generated participant
      */
-    common::id_t generate_participant(
+    std::optional<common::id_t> generate_participant(
         nlohmann::json &parent, common::id_t id, bool force = false) const;
 
     /**
diff --git a/src/sequence_diagram/generators/mermaid/sequence_diagram_generator.cc b/src/sequence_diagram/generators/mermaid/sequence_diagram_generator.cc
index 41bf9390..59e4546f 100644
--- a/src/sequence_diagram/generators/mermaid/sequence_diagram_generator.cc
+++ b/src/sequence_diagram/generators/mermaid/sequence_diagram_generator.cc
@@ -354,7 +354,7 @@ void generator::generate_participant(
 void generator::generate_participant(
     std::ostream &ostr, common::id_t id, bool force) const
 {
-    common::id_t participant_id{0};
+    common::id_t participant_id{};
 
     if (!force) {
         for (const auto pid : model().active_participants()) {
@@ -504,21 +504,21 @@ void generator::generate_diagram(std::ostream &ostr) const
         auto from_activity_id = model().get_from_activity_id(from_location);
         auto to_activity_id = model().get_to_activity_id(to_location);
 
-        if (from_activity_id == 0 || to_activity_id == 0)
+        if (!from_activity_id || !to_activity_id)
             continue;
 
-        if (model().participants().count(from_activity_id) == 0)
+        if (model().participants().count(*from_activity_id) == 0)
             continue;
 
-        if (model().participants().count(to_activity_id) == 0)
+        if (model().participants().count(*to_activity_id) == 0)
             continue;
 
         auto message_chains_unique = model().get_all_from_to_message_chains(
-            from_activity_id, to_activity_id);
+            *from_activity_id, *to_activity_id);
 
         for (const auto &mc : message_chains_unique) {
             const auto &from =
-                model().get_participant<model::function>(from_activity_id);
+                model().get_participant<model::function>(*from_activity_id);
 
             if (from.value().type_name() == "method" ||
                 config().combine_free_functions_into_file_participants()) {
@@ -526,7 +526,7 @@ void generator::generate_diagram(std::ostream &ostr) const
                     ostr << indent(1) << "participant *\n";
                     star_participant_generated = true;
                 }
-                generate_participant(ostr, from_activity_id);
+                generate_participant(ostr, *from_activity_id);
                 ostr << indent(1) << "* "
                      << common::generators::mermaid::to_mermaid(
                             message_t::kCall)
@@ -545,11 +545,11 @@ void generator::generate_diagram(std::ostream &ostr) const
     for (const auto &to_location : config().to()) {
         auto to_activity_id = model().get_to_activity_id(to_location);
 
-        if (to_activity_id == 0)
+        if (!to_activity_id)
             continue;
 
-        auto message_chains_unique =
-            model().get_all_from_to_message_chains(0, to_activity_id);
+        auto message_chains_unique = model().get_all_from_to_message_chains(
+            common::id_t{}, *to_activity_id);
 
         for (const auto &mc : message_chains_unique) {
             const auto from_activity_id = mc.front().from();
@@ -580,7 +580,7 @@ void generator::generate_diagram(std::ostream &ostr) const
 
     for (const auto &sf : config().from()) {
         if (sf.location_type == location_t::function) {
-            common::id_t start_from{0};
+            common::id_t start_from{};
             for (const auto &[k, v] : model().sequences()) {
                 if (model().participants().count(v.from()) == 0)
                     continue;
@@ -649,8 +649,7 @@ void generator::generate_diagram(std::ostream &ostr) const
                     ostr << indent(1) << from_alias << " "
                          << common::generators::mermaid::to_mermaid(
                                 message_t::kReturn)
-                         << " *"
-                         << " : ";
+                         << " *" << " : ";
 
                     if (config().generate_return_types())
                         ostr << from.value().return_type();
diff --git a/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.cc b/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.cc
index 571eca2e..0494beca 100644
--- a/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.cc
+++ b/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.cc
@@ -350,7 +350,7 @@ void generator::generate_participant(
 void generator::generate_participant(
     std::ostream &ostr, common::id_t id, bool force) const
 {
-    common::id_t participant_id{0};
+    common::id_t participant_id{};
 
     if (!force) {
         for (const auto pid : model().active_participants()) {
@@ -508,17 +508,17 @@ void generator::generate_diagram(std::ostream &ostr) const
         auto from_activity_id = model().get_from_activity_id(from_location);
         auto to_activity_id = model().get_to_activity_id(to_location);
 
-        if (from_activity_id == 0 || to_activity_id == 0)
+        if (!from_activity_id || !to_activity_id)
             continue;
 
-        if (model().participants().count(from_activity_id) == 0)
+        if (model().participants().count(*from_activity_id) == 0)
             continue;
 
-        if (model().participants().count(to_activity_id) == 0)
+        if (model().participants().count(*to_activity_id) == 0)
             continue;
 
         auto message_chains_unique = model().get_all_from_to_message_chains(
-            from_activity_id, to_activity_id);
+            *from_activity_id, *to_activity_id);
 
         bool first_separator_skipped{false};
         for (const auto &mc : message_chains_unique) {
@@ -528,11 +528,11 @@ void generator::generate_diagram(std::ostream &ostr) const
                 ostr << "====\n";
 
             const auto &from =
-                model().get_participant<model::function>(from_activity_id);
+                model().get_participant<model::function>(*from_activity_id);
 
             if (from.value().type_name() == "method" ||
                 config().combine_free_functions_into_file_participants()) {
-                generate_participant(ostr, from_activity_id);
+                generate_participant(ostr, *from_activity_id);
                 ostr << "[->"
                      << " " << generate_alias(from.value()) << " : "
                      << from.value().message_name(
@@ -549,11 +549,11 @@ void generator::generate_diagram(std::ostream &ostr) const
     for (const auto &to_location : config().to()) {
         auto to_activity_id = model().get_to_activity_id(to_location);
 
-        if (to_activity_id == 0)
+        if (!to_activity_id)
             continue;
 
         auto message_chains_unique =
-            model().get_all_from_to_message_chains(0, to_activity_id);
+            model().get_all_from_to_message_chains(common::id_t{}, *to_activity_id);
 
         bool first_separator_skipped{false};
         for (const auto &mc : message_chains_unique) {
@@ -588,7 +588,7 @@ void generator::generate_diagram(std::ostream &ostr) const
 
     for (const auto &sf : config().from()) {
         if (sf.location_type == location_t::function) {
-            common::id_t start_from{0};
+            common::id_t start_from{};
             for (const auto &[k, v] : model().sequences()) {
                 if (model().participants().count(v.from()) == 0)
                     continue;
diff --git a/src/sequence_diagram/model/diagram.cc b/src/sequence_diagram/model/diagram.cc
index 5e691f47..98880604 100644
--- a/src/sequence_diagram/model/diagram.cc
+++ b/src/sequence_diagram/model/diagram.cc
@@ -226,10 +226,10 @@ std::vector<std::string> diagram::list_to_values() const
     return result;
 }
 
-common::id_t diagram::get_to_activity_id(
+std::optional<common::id_t> diagram::get_to_activity_id(
     const config::source_location &to_location) const
 {
-    common::id_t to_activity{0};
+    std::optional<common::id_t> to_activity{};
 
     for (const auto &[k, v] : sequences()) {
         for (const auto &m : v.messages()) {
@@ -246,7 +246,7 @@ common::id_t diagram::get_to_activity_id(
         }
     }
 
-    if (to_activity == 0) {
+    if (!to_activity.has_value()) {
         LOG_WARN("Failed to find 'to' participant {} for to "
                  "condition",
             to_location.location);
@@ -255,10 +255,10 @@ common::id_t diagram::get_to_activity_id(
     return to_activity;
 }
 
-common::id_t diagram::get_from_activity_id(
+std::optional<common::id_t> diagram::get_from_activity_id(
     const config::source_location &from_location) const
 {
-    common::id_t from_activity{0};
+    std::optional<common::id_t> from_activity{};
 
     for (const auto &[k, v] : sequences()) {
         const auto &caller = *participants().at(v.from());
@@ -270,7 +270,7 @@ common::id_t diagram::get_from_activity_id(
         }
     }
 
-    if (from_activity == 0) {
+    if (!from_activity.has_value()) {
         LOG_WARN("Failed to find 'from' participant {} for from "
                  "condition",
             from_location.location);
@@ -385,7 +385,7 @@ std::vector<message_chain_t> diagram::get_all_from_to_message_chains(
                 message_chains_unique.end(), mc) != message_chains_unique.end())
             continue;
 
-        if (from_activity == 0 || (mc.front().from() == from_activity)) {
+        if (from_activity.value() == 0 || (mc.front().from() == from_activity)) {
             message_chains_unique.push_back(mc);
         }
     }
diff --git a/src/sequence_diagram/model/diagram.h b/src/sequence_diagram/model/diagram.h
index e269197b..fcbd0009 100644
--- a/src/sequence_diagram/model/diagram.h
+++ b/src/sequence_diagram/model/diagram.h
@@ -267,7 +267,7 @@ public:
      * @param to_location Target activity
      * @return Activity id
      */
-    common::id_t get_to_activity_id(
+    std::optional<common::id_t> get_to_activity_id(
         const config::source_location &to_location) const;
 
     /**
@@ -276,7 +276,7 @@ public:
      * @param from_location Source activity
      * @return Activity id
      */
-    common::id_t get_from_activity_id(
+    std::optional<common::id_t> get_from_activity_id(
         const config::source_location &from_location) const;
 
     /**
diff --git a/src/sequence_diagram/model/participant.cc b/src/sequence_diagram/model/participant.cc
index cf183edb..8c5dbc22 100644
--- a/src/sequence_diagram/model/participant.cc
+++ b/src/sequence_diagram/model/participant.cc
@@ -178,9 +178,9 @@ std::string method::method_name() const { return method_name_; }
 
 std::string method::alias() const
 {
-    assert(class_id_ >= 0);
+    assert(class_id_.value() >= 0);
 
-    return fmt::format("C_{:022}", class_id_);
+    return fmt::format("C_{:022}", class_id_.value());
 }
 
 bool method::is_constructor() const { return is_constructor_; }
diff --git a/src/sequence_diagram/model/participant.h b/src/sequence_diagram/model/participant.h
index 92de35c8..584826eb 100644
--- a/src/sequence_diagram/model/participant.h
+++ b/src/sequence_diagram/model/participant.h
@@ -200,7 +200,7 @@ private:
     bool is_template_instantiation_{false};
     bool is_alias_{false};
     bool is_lambda_{false};
-    common::id_t lambda_operator_id_{0};
+    common::id_t lambda_operator_id_{};
 
     std::string full_name_;
 };
diff --git a/src/sequence_diagram/visitor/call_expression_context.cc b/src/sequence_diagram/visitor/call_expression_context.cc
index 8d49c065..241c9bd7 100644
--- a/src/sequence_diagram/visitor/call_expression_context.cc
+++ b/src/sequence_diagram/visitor/call_expression_context.cc
@@ -24,7 +24,7 @@ call_expression_context::call_expression_context() = default;
 
 void call_expression_context::reset()
 {
-    current_caller_id_ = 0;
+    current_caller_id_ = common::id_t{};
     current_class_decl_ = nullptr;
     current_class_template_decl_ = nullptr;
     current_class_template_specialization_decl_ = nullptr;
@@ -130,33 +130,33 @@ void call_expression_context::update(
     current_function_template_decl_ = function_template;
 }
 
-std::int64_t call_expression_context::caller_id() const
+common::id_t call_expression_context::caller_id() const
 {
-    if (lambda_caller_id() != 0)
-        return lambda_caller_id();
+    if (lambda_caller_id().has_value())
+        return *lambda_caller_id();
 
     return current_caller_id_;
 }
 
-std::int64_t call_expression_context::lambda_caller_id() const
+std::optional<common::id_t> call_expression_context::lambda_caller_id() const
 {
     if (current_lambda_caller_id_.empty())
-        return 0;
+        return {};
 
     return current_lambda_caller_id_.top();
 }
 
-void call_expression_context::set_caller_id(std::int64_t id)
+void call_expression_context::set_caller_id(common::id_t id)
 {
     LOG_DBG("Setting current caller id to {}", id);
     current_caller_id_ = id;
 }
 
-void call_expression_context::enter_lambda_expression(std::int64_t id)
+void call_expression_context::enter_lambda_expression(common::id_t id)
 {
     LOG_DBG("Setting current lambda caller id to {}", id);
 
-    assert(id != 0);
+    assert(id.value() != 0);
 
     current_lambda_caller_id_.push(id);
 }
diff --git a/src/sequence_diagram/visitor/call_expression_context.h b/src/sequence_diagram/visitor/call_expression_context.h
index ba4958f3..38c20dfd 100644
--- a/src/sequence_diagram/visitor/call_expression_context.h
+++ b/src/sequence_diagram/visitor/call_expression_context.h
@@ -116,14 +116,14 @@ struct call_expression_context {
      *
      * @param id Set current caller id.
      */
-    void set_caller_id(std::int64_t id);
+    void set_caller_id(common::id_t id);
 
     /**
      * @brief Get current caller id
      *
      * @return Id of the current caller participant
      */
-    std::int64_t caller_id() const;
+    common::id_t caller_id() const;
 
     /**
      * @brief Get the id of the current lambda caller.
@@ -133,14 +133,14 @@ struct call_expression_context {
      *
      * @return Current lambda caller id, or 0 if current caller is not lambda.
      */
-    std::int64_t lambda_caller_id() const;
+    std::optional<common::id_t> lambda_caller_id() const;
 
     /**
      * @brief Enter a lambda expression
      *
      * @param id Lambda id
      */
-    void enter_lambda_expression(std::int64_t id);
+    void enter_lambda_expression(common::id_t id);
 
     /**
      * @brief Leave current lambda expression
@@ -315,8 +315,8 @@ struct call_expression_context {
     clang::FunctionTemplateDecl *current_function_template_decl_{nullptr};
 
 private:
-    std::int64_t current_caller_id_{0};
-    std::stack<std::int64_t> current_lambda_caller_id_;
+    common::id_t current_caller_id_{};
+    std::stack<common::id_t> current_lambda_caller_id_;
 
     std::stack<callexpr_stack_t> call_expr_stack_;
 
diff --git a/src/sequence_diagram/visitor/translation_unit_visitor.cc b/src/sequence_diagram/visitor/translation_unit_visitor.cc
index 1093cc5f..90b44b52 100644
--- a/src/sequence_diagram/visitor/translation_unit_visitor.cc
+++ b/src/sequence_diagram/visitor/translation_unit_visitor.cc
@@ -64,7 +64,8 @@ bool translation_unit_visitor::VisitCXXRecordDecl(
     // Skip this class if it's parent template is already in the model
     if (declaration->isTemplated() &&
         declaration->getDescribedTemplate() != nullptr) {
-        if (get_unique_id(declaration->getDescribedTemplate()->getID()))
+        if (get_unique_id(
+                common::id_t{declaration->getDescribedTemplate()->getID()}))
             return true;
     }
 
@@ -335,7 +336,8 @@ bool translation_unit_visitor::VisitFunctionDecl(
         if (declaration->getDescribedTemplate() != nullptr) {
             // If the described templated of this function is already in the
             // model skip it:
-            if (get_unique_id(declaration->getDescribedTemplate()->getID()))
+            if (get_unique_id(
+                    common::id_t{declaration->getDescribedTemplate()->getID()}))
                 return true;
         }
     }
@@ -474,7 +476,7 @@ bool translation_unit_visitor::VisitLambdaExpr(clang::LambdaExpr *expr)
     // method function would be excluded by filters
     if (std::holds_alternative<clang::CallExpr *>(
             context().current_callexpr()) &&
-        (context().lambda_caller_id() == 0)) {
+        (!context().lambda_caller_id().has_value())) {
         using clanguml::common::model::message_t;
         using clanguml::sequence_diagram::model::message;
 
@@ -661,7 +663,7 @@ bool translation_unit_visitor::TraverseCompoundStmt(clang::CompoundStmt *stmt)
         if (current_elseifstmt->getElse() == stmt) {
             const auto current_caller_id = context().caller_id();
 
-            if (current_caller_id != 0) {
+            if (current_caller_id.value() != 0) {
                 model::message m{message_t::kElse, current_caller_id};
                 set_source_location(*stmt, m);
                 diagram().add_message(std::move(m));
@@ -672,7 +674,7 @@ bool translation_unit_visitor::TraverseCompoundStmt(clang::CompoundStmt *stmt)
         if (current_ifstmt->getElse() == stmt) {
             const auto current_caller_id = context().caller_id();
 
-            if (current_caller_id != 0) {
+            if (current_caller_id.value() != 0) {
                 model::message m{message_t::kElse, current_caller_id};
                 set_source_location(*stmt, m);
                 diagram().add_message(std::move(m));
@@ -1185,7 +1187,7 @@ bool translation_unit_visitor::VisitCallExpr(clang::CallExpr *expr)
     }
 
     // Add message to diagram
-    if (m.from() > 0 && m.to() > 0) {
+    if (m.from().value() > 0 && m.to().value() > 0) {
         m.set_comment(stripped_comment);
 
         if (diagram().sequences().find(m.from()) ==
@@ -1269,7 +1271,7 @@ bool translation_unit_visitor::VisitCXXConstructExpr(
     if (!process_construct_expression(m, expr))
         return true;
 
-    if (m.from() > 0 && m.to() > 0) {
+    if (m.from().value() > 0 && m.to().value() > 0) {
         if (diagram().sequences().find(m.from()) ==
             diagram().sequences().end()) {
             activity a{m.from()};
@@ -1311,10 +1313,10 @@ bool translation_unit_visitor::process_cuda_kernel_call_expression(
 
     auto callee_name = callee_function->getQualifiedNameAsString() + "()";
 
-    const auto maybe_id = get_unique_id(callee_function->getID());
+    const auto maybe_id = get_unique_id(common::id_t{callee_function->getID()});
     if (!maybe_id.has_value()) {
         // This is hopefully not an interesting call...
-        m.set_to(callee_function->getID());
+        m.set_to(common::id_t{callee_function->getID()});
     }
     else {
         m.set_to(maybe_id.value());
@@ -1349,16 +1351,17 @@ bool translation_unit_visitor::process_operator_call_expression(
 
         auto lambda_name = make_lambda_name(lambda_method->getParent());
 
-        m.set_to(lambda_method->getParent()->getID());
+        m.set_to(common::id_t{lambda_method->getParent()->getID()});
     }
     else {
-        auto maybe_id =
-            get_unique_id(operator_call_expr->getCalleeDecl()->getID());
+        auto maybe_id = get_unique_id(
+            common::id_t{operator_call_expr->getCalleeDecl()->getID()});
         if (maybe_id.has_value()) {
             m.set_to(maybe_id.value());
         }
         else {
-            m.set_to(operator_call_expr->getCalleeDecl()->getID());
+            m.set_to(
+                common::id_t{operator_call_expr->getCalleeDecl()->getID()});
         }
     }
 
@@ -1384,19 +1387,19 @@ bool translation_unit_visitor::process_construct_expression(
         constructor->getID(),
         construct_expr->getBeginLoc().printToString(source_manager()));
 
-    auto maybe_id = get_unique_id(constructor->getID());
+    auto maybe_id = get_unique_id(common::id_t{constructor->getID()});
     if (maybe_id.has_value()) {
         m.set_to(maybe_id.value());
     }
     else {
-        m.set_to(constructor->getID());
+        m.set_to(common::id_t{constructor->getID()});
     }
 
     m.set_message_name(
         fmt::format("{}::{}", constructor_parent->getQualifiedNameAsString(),
             constructor_parent->getNameAsString()));
 
-    diagram().add_active_participant(constructor->getID());
+    diagram().add_active_participant(common::id_t{constructor->getID()});
 
     return true;
 }
@@ -1421,7 +1424,7 @@ bool translation_unit_visitor::process_class_method_call_expression(
     if (!should_include(callee_decl) || !should_include(method_decl))
         return false;
 
-    m.set_to(method_decl->getID());
+    m.set_to(common::id_t{method_decl->getID()});
     m.set_message_name(method_decl->getNameAsString());
     m.set_return_type(
         method_call_expr->getCallReturnType(*context().get_ast_context())
@@ -1430,7 +1433,7 @@ bool translation_unit_visitor::process_class_method_call_expression(
     LOG_TRACE("Set callee method id {} for method name {}", m.to(),
         method_decl->getQualifiedNameAsString());
 
-    diagram().add_active_participant(method_decl->getID());
+    diagram().add_active_participant(common::id_t{method_decl->getID()});
 
     return true;
 }
@@ -1507,7 +1510,7 @@ bool translation_unit_visitor::process_class_template_method_call_expression(
                 dependent_member_callee->getMember().getAsString());
 
             if (const auto maybe_id =
-                    get_unique_id(template_declaration->getID());
+                    get_unique_id(common::id_t{template_declaration->getID()});
                 maybe_id.has_value())
                 diagram().add_active_participant(maybe_id.value());
         }
@@ -1544,10 +1547,10 @@ bool translation_unit_visitor::process_function_call_expression(
 
     auto callee_name = callee_function->getQualifiedNameAsString() + "()";
 
-    const auto maybe_id = get_unique_id(callee_function->getID());
+    const auto maybe_id = get_unique_id(common::id_t{callee_function->getID()});
     if (!maybe_id.has_value()) {
         // This is hopefully not an interesting call...
-        m.set_to(callee_function->getID());
+        m.set_to(common::id_t{callee_function->getID()});
     }
     else {
         m.set_to(maybe_id.value());
@@ -1567,7 +1570,8 @@ bool translation_unit_visitor::process_lambda_call_expression(
     if (lambda_expr == nullptr)
         return true;
 
-    const auto lambda_class_id = lambda_expr->getLambdaClass()->getID();
+    const auto lambda_class_id =
+        common::id_t{lambda_expr->getLambdaClass()->getID()};
     const auto maybe_id = get_unique_id(lambda_class_id);
     if (!maybe_id.has_value())
         m.set_to(lambda_class_id);
@@ -1592,9 +1596,9 @@ bool translation_unit_visitor::process_unresolved_lookup_call_expression(
                 const auto *ftd =
                     clang::dyn_cast_or_null<clang::FunctionTemplateDecl>(decl);
 
-                const auto maybe_id = get_unique_id(ftd->getID());
+                const auto maybe_id = get_unique_id(common::id_t{ftd->getID()});
                 if (!maybe_id.has_value())
-                    m.set_to(ftd->getID());
+                    m.set_to(common::id_t{ftd->getID()});
                 else {
                     m.set_to(maybe_id.value());
                 }
@@ -1606,9 +1610,9 @@ bool translation_unit_visitor::process_unresolved_lookup_call_expression(
                 const auto *fd =
                     clang::dyn_cast_or_null<clang::FunctionDecl>(decl);
 
-                const auto maybe_id = get_unique_id(fd->getID());
+                const auto maybe_id = get_unique_id(common::id_t{fd->getID()});
                 if (!maybe_id.has_value())
-                    m.set_to(fd->getID());
+                    m.set_to(common::id_t{fd->getID()});
                 else {
                     m.set_to(maybe_id.value());
                 }
@@ -1684,18 +1688,18 @@ translation_unit_visitor::create_class_model(clang::CXXRecordDecl *cls)
 
         assert(parent_record_decl != nullptr);
 
-        int64_t local_id = parent_record_decl->getID();
+        const common::id_t ast_id{parent_record_decl->getID()};
 
         // First check if the parent has been added to the diagram as
         // regular class
-        id_opt = get_unique_id(local_id);
+        id_opt = get_unique_id(ast_id);
 
         // If not, check if the parent template declaration is in the model
         if (!id_opt &&
             (parent_record_decl->getDescribedTemplate() != nullptr)) {
             parent_record_decl->getDescribedTemplate()->getID();
             if (parent_record_decl->getDescribedTemplate() != nullptr)
-                id_opt = get_unique_id(local_id);
+                id_opt = get_unique_id(ast_id);
         }
 
         if (!id_opt)
@@ -1778,12 +1782,13 @@ void translation_unit_visitor::set_unique_id(
 }
 
 std::optional<common::id_t> translation_unit_visitor::get_unique_id(
-    int64_t local_id) const
+    common::id_t local_id) const
 {
-    if (local_ast_id_map_.find(local_id) == local_ast_id_map_.end())
+    if (local_ast_id_map_.find(local_id.ast_local_value()) ==
+        local_ast_id_map_.end())
         return {};
 
-    return local_ast_id_map_.at(local_id);
+    return local_ast_id_map_.at(local_id.ast_local_value());
 }
 
 std::unique_ptr<model::function_template>
@@ -1927,13 +1932,15 @@ std::string translation_unit_visitor::make_lambda_name(
     if (context().lambda_caller_id() != 0) {
         // Parent is also a lambda (this id points to a lambda operator())
         std::string parent_lambda_class_name{"()"};
-        if (diagram().get_participant<model::method>(
-                context().lambda_caller_id())) {
-            auto parent_lambda_class_id = diagram()
-                                              .get_participant<model::method>(
-                                                  context().lambda_caller_id())
-                                              .value()
-                                              .class_id();
+        if (context().lambda_caller_id() &&
+            diagram().get_participant<model::method>(
+                context().lambda_caller_id().value())) {
+            auto parent_lambda_class_id =
+                diagram()
+                    .get_participant<model::method>(
+                        context().lambda_caller_id().value())
+                    .value()
+                    .class_id();
 
             if (diagram().get_participant<model::class_>(
                     parent_lambda_class_id)) {
@@ -2054,8 +2061,11 @@ void translation_unit_visitor::resolve_ids_to_global()
 
     // Change all active participants AST local ids to diagram global ids
     for (auto id : diagram().active_participants()) {
-        if (local_ast_id_map_.find(id) != local_ast_id_map_.end()) {
-            active_participants_unique.emplace(local_ast_id_map_.at(id));
+        if (!id.is_global() &&
+            local_ast_id_map_.find(id.ast_local_value()) !=
+                local_ast_id_map_.end()) {
+            active_participants_unique.emplace(
+                local_ast_id_map_.at(id.ast_local_value()));
         }
         else {
             active_participants_unique.emplace(id);
@@ -2067,8 +2077,10 @@ void translation_unit_visitor::resolve_ids_to_global()
     // Change all message callees AST local ids to diagram global ids
     for (auto &[id, activity] : diagram().sequences()) {
         for (auto &m : activity.messages()) {
-            if (local_ast_id_map_.find(m.to()) != local_ast_id_map_.end()) {
-                m.set_to(local_ast_id_map_.at(m.to()));
+            if (!id.is_global() &&
+                local_ast_id_map_.find(m.to().ast_local_value()) !=
+                    local_ast_id_map_.end()) {
+                m.set_to(local_ast_id_map_.at(m.to().ast_local_value()));
             }
         }
     }
@@ -2280,7 +2292,7 @@ bool translation_unit_visitor::should_include(
 
 std::optional<std::string> translation_unit_visitor::get_expression_comment(
     const clang::SourceManager &sm, const clang::ASTContext &context,
-    const int64_t caller_id, const clang::Stmt *stmt)
+    const common::id_t caller_id, const clang::Stmt *stmt)
 {
     const auto *raw_comment =
         clanguml::common::get_expression_raw_comment(sm, context, stmt);
@@ -2288,7 +2300,8 @@ std::optional<std::string> translation_unit_visitor::get_expression_comment(
     if (raw_comment == nullptr)
         return {};
 
-    if (!processed_comments_by_caller_id_.emplace(caller_id, raw_comment)
+    if (!processed_comments_by_caller_id_
+             .emplace(caller_id.ast_local_value(), raw_comment)
              .second) {
         return {};
     }
diff --git a/src/sequence_diagram/visitor/translation_unit_visitor.h b/src/sequence_diagram/visitor/translation_unit_visitor.h
index 071509b9..d5f3b717 100644
--- a/src/sequence_diagram/visitor/translation_unit_visitor.h
+++ b/src/sequence_diagram/visitor/translation_unit_visitor.h
@@ -166,7 +166,7 @@ public:
     {
         assert(decl != nullptr);
 
-        auto unique_participant_id = get_unique_id(decl->getID());
+        auto unique_participant_id = get_unique_id(common::id_t{decl->getID()});
         if (!unique_participant_id.has_value())
             return {};
 
@@ -185,7 +185,7 @@ public:
     {
         assert(decl != nullptr);
 
-        auto unique_participant_id = get_unique_id(decl->getID());
+        auto unique_participant_id = get_unique_id(common::id_t{decl->getID()});
         if (!unique_participant_id.has_value())
             return {};
 
@@ -243,7 +243,7 @@ public:
      * @param local_id AST local element id
      * @return Global diagram element id
      */
-    std::optional<common::id_t> get_unique_id(int64_t local_id) const;
+    std::optional<common::id_t> get_unique_id(common::id_t local_id) const;
 
     /**
      * @brief Finalize diagram model for this translation unit
@@ -469,7 +469,7 @@ private:
 
     std::optional<std::string> get_expression_comment(
         const clang::SourceManager &sm, const clang::ASTContext &context,
-        int64_t caller_id, const clang::Stmt *stmt);
+        common::id_t caller_id, const clang::Stmt *stmt);
 
     /**
      * @brief Initializes model message from comment call directive