diff --git a/src/config/config.h b/src/config/config.h
index 87ca1506..82e0daae 100644
--- a/src/config/config.h
+++ b/src/config/config.h
@@ -39,6 +39,17 @@ struct plantuml {
 
 struct filter {
     std::vector<std::string> namespaces;
+
+    // Valid values are:
+    //   - inheritance
+    //   - dependency
+    //   - instantiation
+    std::vector<std::string> relationships;
+
+    // E.g.:
+    //   - classes
+    //   - enums
+    std::vector<std::string> entity_types;
 };
 
 struct diagram {
@@ -53,6 +64,42 @@ struct diagram {
 
     plantuml puml;
 
+    bool should_include_entities(const std::string &ent)
+    {
+        for (const auto &ex : exclude.entity_types) {
+            if (ent == ex)
+                return false;
+        }
+
+        if (include.entity_types.empty())
+            return true;
+
+        for (const auto &in : include.entity_types) {
+            if (ent == in)
+                return true;
+        }
+
+        return false;
+    }
+
+    bool should_include_relationship(const std::string &rel)
+    {
+        for (const auto &ex : exclude.relationships) {
+            if (rel == ex)
+                return false;
+        }
+
+        if (include.relationships.empty())
+            return true;
+
+        for (const auto &in : include.relationships) {
+            if (rel == in)
+                return true;
+        }
+
+        return false;
+    }
+
     bool should_include(const std::string &name_) const
     {
         auto name = clanguml::util::unqualify(name_);
@@ -186,6 +233,15 @@ template <> struct convert<filter> {
     {
         if (node["namespaces"])
             rhs.namespaces = node["namespaces"].as<decltype(rhs.namespaces)>();
+
+        if (node["relationships"])
+            rhs.relationships =
+                node["relationships"].as<decltype(rhs.relationships)>();
+
+        if (node["entity_types"])
+            rhs.entity_types =
+                node["entity_types"].as<decltype(rhs.entity_types)>();
+
         return true;
     }
 };
diff --git a/src/puml/class_diagram_generator.h b/src/puml/class_diagram_generator.h
index 79a56f62..94a7fbfb 100644
--- a/src/puml/class_diagram_generator.h
+++ b/src/puml/class_diagram_generator.h
@@ -101,6 +101,29 @@ public:
         }
     }
 
+    std::string name(relationship_t r) const
+    {
+        switch (r) {
+        case relationship_t::kOwnership:
+        case relationship_t::kComposition:
+            return "composition";
+        case relationship_t::kAggregation:
+            return "aggregation";
+        case relationship_t::kContainment:
+            return "containment";
+        case relationship_t::kAssociation:
+            return "association";
+        case relationship_t::kInstantiation:
+            return "instantiation";
+        case relationship_t::kFriendship:
+            return "friendship";
+        case relationship_t::kDependency:
+            return "dependency";
+        default:
+            return "unknown";
+        }
+    }
+
     void generate_aliases(const class_ &c, std::ostream &ostr) const
     {
         std::string class_type{"class"};
@@ -176,16 +199,20 @@ public:
 
         ostr << "}" << std::endl;
 
-        for (const auto &b : c.bases) {
-            ostr << m_model.to_alias(m_config.using_namespace,
-                        ns_relative(m_config.using_namespace, b.name))
-                 << " <|-- "
-                 << m_model.to_alias(m_config.using_namespace,
-                        ns_relative(m_config.using_namespace, c.name))
-                 << std::endl;
-        }
+        if (m_config.should_include_relationship("inheritance"))
+            for (const auto &b : c.bases) {
+                ostr << m_model.to_alias(m_config.using_namespace,
+                            ns_relative(m_config.using_namespace, b.name))
+                     << " <|-- "
+                     << m_model.to_alias(m_config.using_namespace,
+                            ns_relative(m_config.using_namespace, c.name))
+                     << std::endl;
+            }
 
         for (const auto &r : c.relationships) {
+            if (!m_config.should_include_relationship(name(r.type)))
+                continue;
+
             std::string destination;
             if (r.destination.find("#") != std::string::npos ||
                 r.destination.find("@") != std::string::npos) {
@@ -226,6 +253,9 @@ public:
         ostr << "}" << std::endl;
 
         for (const auto &r : e.relationships) {
+            if (!m_config.should_include_relationship(name(r.type)))
+                continue;
+
             std::string destination;
             if (r.destination.find("#") != std::string::npos ||
                 r.destination.find("@") != std::string::npos) {
@@ -260,20 +290,23 @@ public:
         for (const auto &b : m_config.puml.before)
             ostr << b << std::endl;
 
-        for (const auto &c : m_model.classes) {
-            generate_aliases(c, ostr);
-            ostr << std::endl;
+        if (m_config.should_include_entities("classes")) {
+            for (const auto &c : m_model.classes) {
+                generate_aliases(c, ostr);
+                ostr << std::endl;
+            }
+
+            for (const auto &c : m_model.classes) {
+                generate(c, ostr);
+                ostr << std::endl;
+            }
         }
 
-        for (const auto &c : m_model.classes) {
-            generate(c, ostr);
-            ostr << std::endl;
-        }
-
-        for (const auto &e : m_model.enums) {
-            generate(e, ostr);
-            ostr << std::endl;
-        }
+        if (m_config.should_include_entities("enums"))
+            for (const auto &e : m_model.enums) {
+                generate(e, ostr);
+                ostr << std::endl;
+            }
 
         for (const auto &b : m_config.puml.after)
             ostr << b << std::endl;
diff --git a/src/uml/class_diagram_visitor.cc b/src/uml/class_diagram_visitor.cc
index 57426648..49774ae0 100644
--- a/src/uml/class_diagram_visitor.cc
+++ b/src/uml/class_diagram_visitor.cc
@@ -75,13 +75,15 @@ void tu_visitor::operator()(const cppast::cpp_entity &file)
                     cx::util::full_name(e), cppast::to_string(e.kind()));
 
                 auto &cls = static_cast<const cppast::cpp_class &>(e);
-                auto &clsdef = static_cast<const cppast::cpp_class &>(
-                    cppast::get_definition(ctx.entity_index, cls).value());
-                if (&cls != &clsdef) {
-                    spdlog::debug(
-                        "Forward declaration of class {} - skipping...",
-                        cls.name());
-                    return;
+                if (cppast::get_definition(ctx.entity_index, cls)) {
+                    auto &clsdef = static_cast<const cppast::cpp_class &>(
+                        cppast::get_definition(ctx.entity_index, cls).value());
+                    if (&cls != &clsdef) {
+                        spdlog::debug(
+                            "Forward declaration of class {} - skipping...",
+                            cls.name());
+                        return;
+                    }
                 }
                 if (ctx.config.should_include(cx::util::fully_prefixed(cls)))
                     process_class_declaration(cls);
diff --git a/tests/t00014/t00014.cc b/tests/t00014/t00014.cc
index 403cf616..12791b89 100644
--- a/tests/t00014/t00014.cc
+++ b/tests/t00014/t00014.cc
@@ -18,12 +18,13 @@ template <typename T> using AString = A<T, std::string>;
 
 using AIntString = AString<int>;
 using AStringString = AString<std::string>;
+using BStringString = AStringString;
 
 class R {
     A<bool, std::string> boolstring;
     AString<float> floatstring;
     AIntString intstring;
-    AStringString stringstring;
+    BStringString stringstring;
 };
 }
 }