diff --git a/servers/navigation/navigation_mesh_generator.cpp b/servers/navigation/navigation_mesh_generator.cpp
index 96b44126c..25048122b 100644
--- a/servers/navigation/navigation_mesh_generator.cpp
+++ b/servers/navigation/navigation_mesh_generator.cpp
@@ -97,17 +97,16 @@ void NavigationMeshGeneratorManager::on_servers_changed() {
 }
 
 void NavigationMeshGeneratorManager::_bind_methods() {
-	ClassDB::bind_method(D_METHOD("register_server", "name", "create_callback"), &NavigationMeshGeneratorManager::register_server);
-	ClassDB::bind_method(D_METHOD("set_default_server", "name", "priority"), &NavigationMeshGeneratorManager::set_default_server);
+	//ClassDB::bind_method(D_METHOD("register_server", "name", "create_callback"), &NavigationMeshGeneratorManager::register_server);
+	//ClassDB::bind_method(D_METHOD("set_default_server", "name", "priority"), &NavigationMeshGeneratorManager::set_default_server);
 }
 
 NavigationMeshGeneratorManager *NavigationMeshGeneratorManager::get_singleton() {
 	return singleton;
 }
 
-void NavigationMeshGeneratorManager::register_server(const String &p_name, const Ref<FuncRef> &p_create_callback) {
-	// TODO: Enable check when is_valid() is fixed for static functions.
-	//ERR_FAIL_COND(!p_create_callback.is_valid());
+void NavigationMeshGeneratorManager::register_server(const String &p_name, CreateNavigationMeshGeneratorCallback p_create_callback) {
+	ERR_FAIL_COND(!p_create_callback);
 	ERR_FAIL_COND_MSG(find_server_id(p_name) != -1, "NavigationMeshGenerator with the same name was already registered.");
 
 	navigation_mesh_generators.push_back(ClassInfo{ p_name, p_create_callback });
@@ -138,17 +137,7 @@ int NavigationMeshGeneratorManager::find_server_id(const String &p_name) const {
 NavigationMeshGenerator *NavigationMeshGeneratorManager::new_default_server() const {
 	ERR_FAIL_COND_V(default_server_id == -1, nullptr);
 
-	Ref<FuncRef> fr = navigation_mesh_generators[default_server_id].create_callback;
-
-	ERR_FAIL_COND_V(!fr.is_valid(), nullptr);
-	Array arr;
-	Variant ret = fr->call_funcv(arr);
-
-	ERR_FAIL_COND_V(ret.is_invalid_object(), nullptr);
-
-	Object *o = ObjectDB::get_instance(ret.get_object_instance_id());
-
-	NavigationMeshGenerator *gen = Object::cast_to<NavigationMeshGenerator>(o);
+	NavigationMeshGenerator *gen = navigation_mesh_generators[default_server_id].create_callback();
 
 	ERR_FAIL_COND_V(!gen, nullptr);
 
@@ -162,17 +151,7 @@ NavigationMeshGenerator *NavigationMeshGeneratorManager::new_server(const String
 		return nullptr;
 	}
 
-	Ref<FuncRef> fr = navigation_mesh_generators[id].create_callback;
-
-	ERR_FAIL_COND_V(!fr.is_valid(), nullptr);
-	Array arr;
-	Variant ret = fr->call_funcv(arr);
-
-	ERR_FAIL_COND_V(ret.is_invalid_object(), nullptr);
-
-	Object *o = ObjectDB::get_instance(ret.get_object_instance_id());
-
-	NavigationMeshGenerator *gen = Object::cast_to<NavigationMeshGenerator>(o);
+	NavigationMeshGenerator *gen = navigation_mesh_generators[id].create_callback();
 
 	ERR_FAIL_COND_V(!gen, nullptr);
 
diff --git a/servers/navigation/navigation_mesh_generator.h b/servers/navigation/navigation_mesh_generator.h
index ec5391e76..940dc3f1e 100644
--- a/servers/navigation/navigation_mesh_generator.h
+++ b/servers/navigation/navigation_mesh_generator.h
@@ -33,8 +33,8 @@
 
 #include "core/containers/rid.h"
 #include "core/object/class_db.h"
-#include "core/object/reference.h"
 #include "core/object/func_ref.h"
+#include "core/object/reference.h"
 
 class Node;
 class NavigationGeometryParser2D;
@@ -89,6 +89,8 @@ public:
 
 /// NavigationMeshGeneratorManager ////////////////////////////////////////////////////
 
+typedef NavigationMeshGenerator *(*CreateNavigationMeshGeneratorCallback)();
+
 class NavigationMeshGeneratorManager : public Object {
 	GDCLASS(NavigationMeshGeneratorManager, Object);
 
@@ -96,7 +98,7 @@ class NavigationMeshGeneratorManager : public Object {
 
 	struct ClassInfo {
 		String name;
-		Ref<FuncRef> create_callback;
+		CreateNavigationMeshGeneratorCallback create_callback;
 	};
 
 	Vector<ClassInfo> navigation_mesh_generators;
@@ -113,7 +115,7 @@ public:
 
 	static NavigationMeshGeneratorManager *get_singleton();
 
-	void register_server(const String &p_name, const Ref<FuncRef> &p_create_callback);
+	void register_server(const String &p_name, CreateNavigationMeshGeneratorCallback p_create_callback);
 	void set_default_server(const String &p_name, int p_priority = 0);
 	int find_server_id(const String &p_name) const;