diff --git a/src/uml/class_diagram_model.h b/src/uml/class_diagram_model.h
index 42631573..52a27e9b 100644
--- a/src/uml/class_diagram_model.h
+++ b/src/uml/class_diagram_model.h
@@ -131,6 +131,11 @@ struct class_template {
     std::string type;
     std::string default_value;
     bool is_variadic{false};
+
+    friend bool operator==(const class_template &l, const class_template &r)
+    {
+        return (l.name == r.name) && (l.type == r.type);
+    }
 };
 
 class class_ : public element {
@@ -147,6 +152,11 @@ public:
     std::vector<class_template> templates;
     std::string base_template_usr;
 
+    friend bool operator==(const class_ &l, const class_ &r)
+    {
+        return (l.usr == r.usr) && (l.templates == r.templates);
+    }
+
     void add_relationship(class_relationship &&cr)
     {
         auto it = std::find(relationships.begin(), relationships.end(), cr);
@@ -201,6 +211,11 @@ public:
 
 struct enum_ : public element {
     std::vector<std::string> constants;
+
+    friend bool operator==(const enum_ &l, const enum_ &r)
+    {
+        return l.name == r.name;
+    }
 };
 
 struct diagram {
@@ -208,6 +223,21 @@ struct diagram {
     std::vector<class_> classes;
     std::vector<enum_> enums;
 
+    void add_class(class_ &&c)
+    {
+        spdlog::debug("ADDING CLASS: {}, {}", c.name, c.usr);
+        auto it = std::find(classes.begin(), classes.end(), c);
+        if (it == classes.end())
+            classes.emplace_back(std::move(c));
+    }
+
+    void add_enum(enum_ &&e)
+    {
+        auto it = std::find(enums.begin(), enums.end(), e);
+        if (it == enums.end())
+            enums.emplace_back(std::move(e));
+    }
+
     std::string to_alias(const std::vector<std::string> &using_namespaces,
         const std::string &full_name) const
     {
diff --git a/src/uml/class_diagram_visitor.cc b/src/uml/class_diagram_visitor.cc
index 98d01069..80b027fe 100644
--- a/src/uml/class_diagram_visitor.cc
+++ b/src/uml/class_diagram_visitor.cc
@@ -237,7 +237,7 @@ enum CXChildVisitResult method_parameter_visitor(
 
                         r.destination = t.referenced().unqualified();
 
-                        ctx->d.classes.emplace_back(std::move(tinst));
+                        ctx->d.add_class(std::move(tinst));
                     }
                     else
                         r.destination = t.referenced().type_declaration().usr();
@@ -453,7 +453,7 @@ enum CXChildVisitResult process_class_declaration(
         spdlog::debug("Added relationship {} +-- {}", parent->name, c.name);
     }
 
-    ctx->d.classes.emplace_back(std::move(c));
+    ctx->d.add_class(std::move(c));
 
     return CXChildVisit_Continue;
 }
@@ -482,7 +482,7 @@ enum CXChildVisitResult process_enum_declaration(
         spdlog::debug("Added relationship {} +-- {}", parent->name, e.name);
     }
 
-    ctx->d.enums.emplace_back(std::move(e));
+    ctx->d.add_enum(std::move(e));
 
     return CXChildVisit_Continue;
 }
@@ -569,7 +569,7 @@ bool process_template_specialization_class_field(
 
         tinst.add_relationship(std::move(r));
 
-        ctx->d.classes.emplace_back(std::move(tinst));
+        ctx->d.add_class(std::move(tinst));
         return true;
     }
 
diff --git a/tests/t00013/t00013.cc b/tests/t00013/t00013.cc
index cb5821e0..d6c4c2d8 100644
--- a/tests/t00013/t00013.cc
+++ b/tests/t00013/t00013.cc
@@ -48,6 +48,7 @@ public:
 
     template <typename T> T get_e(E<T> &e) { return e.e; }
     int get_int_e(const E<int> &e) { return e.e; }
+    int get_int_e2(E<int> &e) { return e.e; }
 
     template <typename T> T get_f(const F<T> &f) { return f.f; }