diff --git a/src/class_diagram/model/class_parent.h b/src/class_diagram/model/class_parent.h
index 62b39029..d1afd485 100644
--- a/src/class_diagram/model/class_parent.h
+++ b/src/class_diagram/model/class_parent.h
@@ -41,9 +41,9 @@ public:
     common::model::access_t access() const;
 
 private:
-    clanguml::common::id_t id_;
+    clanguml::common::id_t id_{};
     std::string name_;
     bool is_virtual_{false};
-    common::model::access_t access_;
+    common::model::access_t access_{common::model::access_t::kPublic};
 };
 } // namespace clanguml::class_diagram::model
diff --git a/src/common/model/diagram_element.cc b/src/common/model/diagram_element.cc
index 8571ffeb..20f23a85 100644
--- a/src/common/model/diagram_element.cc
+++ b/src/common/model/diagram_element.cc
@@ -26,12 +26,7 @@ namespace clanguml::common::model {
 
 std::atomic_uint64_t diagram_element::m_nextId = 1;
 
-diagram_element::diagram_element()
-    : id_{0}
-    , nested_{false}
-    , complete_{false}
-{
-}
+diagram_element::diagram_element() { }
 
 diagram_element::id_t diagram_element::id() const { return id_; }
 
diff --git a/src/common/model/diagram_element.h b/src/common/model/diagram_element.h
index 91806fe2..2553f87c 100644
--- a/src/common/model/diagram_element.h
+++ b/src/common/model/diagram_element.h
@@ -77,11 +77,11 @@ public:
     void complete(bool completed);
 
 private:
-    id_t id_;
+    id_t id_{0};
     std::string name_;
     std::vector<relationship> relationships_;
-    bool nested_;
-    bool complete_;
+    bool nested_{false};
+    bool complete_{false};
 
     static std::atomic_uint64_t m_nextId;
 };
diff --git a/src/common/model/source_location.h b/src/common/model/source_location.h
index 89525c66..3bdae624 100644
--- a/src/common/model/source_location.h
+++ b/src/common/model/source_location.h
@@ -47,6 +47,6 @@ public:
 private:
     std::string file_;
     unsigned int line_{0};
-    unsigned int hash_;
+    unsigned int hash_{0};
 };
 } // namespace clanguml::common::model
\ No newline at end of file
diff --git a/src/common/types.h b/src/common/types.h
index 4cabddea..b0176495 100644
--- a/src/common/types.h
+++ b/src/common/types.h
@@ -31,10 +31,7 @@ template <typename T> class optional_ref {
 public:
     using optional_type = T;
 
-    optional_ref()
-        : value_{nullptr}
-    {
-    }
+    optional_ref() { }
 
     optional_ref(T *value) { value_ = value; }
 
@@ -112,7 +109,7 @@ public:
     T *get() const { return value_; }
 
 private:
-    T *value_;
+    T *value_{nullptr};
 };
 
 template <typename T>
diff --git a/src/config/config.h b/src/config/config.h
index 8d34197a..72271190 100644
--- a/src/config/config.h
+++ b/src/config/config.h
@@ -79,7 +79,7 @@ struct filter {
 enum class hint_t { up, down, left, right };
 
 struct layout_hint {
-    hint_t hint;
+    hint_t hint{hint_t::up};
     std::string entity;
 };
 
@@ -166,7 +166,7 @@ struct diagram : public inheritable_diagram_options {
 
 struct source_location {
     enum class location_t { usr, marker, fileline, function };
-    location_t location_type;
+    location_t location_type{location_t::function};
     std::string location;
 };
 
diff --git a/src/sequence_diagram/model/participant.h b/src/sequence_diagram/model/participant.h
index 630ffc09..e5b518a7 100644
--- a/src/sequence_diagram/model/participant.h
+++ b/src/sequence_diagram/model/participant.h
@@ -206,7 +206,7 @@ struct method : public function {
     std::string to_string() const override;
 
 private:
-    diagram_element::id_t class_id_;
+    diagram_element::id_t class_id_{};
     std::string method_name_;
     std::string class_full_name_;
 };
diff --git a/src/sequence_diagram/visitor/call_expression_context.cc b/src/sequence_diagram/visitor/call_expression_context.cc
index b82b4851..fbbb4e51 100644
--- a/src/sequence_diagram/visitor/call_expression_context.cc
+++ b/src/sequence_diagram/visitor/call_expression_context.cc
@@ -20,16 +20,7 @@
 
 namespace clanguml::sequence_diagram::visitor {
 
-call_expression_context::call_expression_context()
-    : current_class_decl_{nullptr}
-    , current_class_template_decl_{nullptr}
-    , current_class_template_specialization_decl_{nullptr}
-    , current_method_decl_{nullptr}
-    , current_function_decl_{nullptr}
-    , current_function_template_decl_{nullptr}
-    , current_caller_id_{0}
-{
-}
+call_expression_context::call_expression_context() { }
 
 void call_expression_context::reset()
 {
diff --git a/src/sequence_diagram/visitor/call_expression_context.h b/src/sequence_diagram/visitor/call_expression_context.h
index e124770e..6777b189 100644
--- a/src/sequence_diagram/visitor/call_expression_context.h
+++ b/src/sequence_diagram/visitor/call_expression_context.h
@@ -99,16 +99,16 @@ struct call_expression_context {
     bool is_expr_in_current_control_statement_condition(
         const clang::Stmt *stmt) const;
 
-    clang::CXXRecordDecl *current_class_decl_;
-    clang::ClassTemplateDecl *current_class_template_decl_;
+    clang::CXXRecordDecl *current_class_decl_{nullptr};
+    clang::ClassTemplateDecl *current_class_template_decl_{nullptr};
     clang::ClassTemplateSpecializationDecl
-        *current_class_template_specialization_decl_;
-    clang::CXXMethodDecl *current_method_decl_;
-    clang::FunctionDecl *current_function_decl_;
-    clang::FunctionTemplateDecl *current_function_template_decl_;
+        *current_class_template_specialization_decl_{nullptr};
+    clang::CXXMethodDecl *current_method_decl_{nullptr};
+    clang::FunctionDecl *current_function_decl_{nullptr};
+    clang::FunctionTemplateDecl *current_function_template_decl_{nullptr};
 
 private:
-    std::int64_t current_caller_id_;
+    std::int64_t current_caller_id_{0};
     std::stack<std::int64_t> current_lambda_caller_id_;
 
     std::stack<clang::CallExpr *> call_expr_stack_;