diff --git a/include/graphqlservice/GraphQLService.h b/include/graphqlservice/GraphQLService.h
index ebd026a1..4c020298 100644
--- a/include/graphqlservice/GraphQLService.h
+++ b/include/graphqlservice/GraphQLService.h
@@ -663,9 +663,11 @@ struct ModifiedArgument
 
 	// Peel off the none modifier. If it's included, it should always be last in the list.
 	template <TypeModifier Modifier = TypeModifier::None, TypeModifier... Other>
-	static typename std::enable_if_t<TypeModifier::None == Modifier && sizeof...(Other) == 0, Type>
-	require(std::string_view name, const response::Value& arguments)
+	static typename std::enable_if_t<TypeModifier::None == Modifier, Type> require(
+		std::string_view name, const response::Value& arguments)
 	{
+		static_assert(sizeof...(Other) == 0, "None modifier should always be last");
+
 		// Just call through to the non-template method without the modifiers.
 		return require(name, arguments);
 	}
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 7e594f3e..abd456f6 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -452,6 +452,7 @@ install(FILES
     ${CMAKE_CURRENT_SOURCE_DIR}/../include/graphqlservice/internal/Awaitable.h
     ${CMAKE_CURRENT_SOURCE_DIR}/../include/graphqlservice/internal/Base64.h
     ${CMAKE_CURRENT_SOURCE_DIR}/../include/graphqlservice/internal/Grammar.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/../include/graphqlservice/internal/Introspection.h
     ${CMAKE_CURRENT_SOURCE_DIR}/../include/graphqlservice/internal/Schema.h
     ${CMAKE_CURRENT_SOURCE_DIR}/../include/graphqlservice/internal/SortedMap.h
     ${CMAKE_CURRENT_SOURCE_DIR}/../include/graphqlservice/internal/SyntaxTree.h
diff --git a/src/SchemaGenerator.cpp b/src/SchemaGenerator.cpp
index 492a736c..580fe487 100644
--- a/src/SchemaGenerator.cpp
+++ b/src/SchemaGenerator.cpp
@@ -2874,7 +2874,7 @@ using namespace std::literals;
 
 		if (!_loader.isIntrospection())
 		{
-			if (!objectType.interfaces.empty())
+			if (!objectType.interfaces.empty() || !objectType.unions.empty())
 			{
 				NamespaceScope implementsNamespace { headerFile, R"cpp(implements)cpp" };