diff --git a/modules/fbx/fbx_document.cpp b/modules/fbx/fbx_document.cpp
index 367117edcbef..1dbe4c535ad6 100644
--- a/modules/fbx/fbx_document.cpp
+++ b/modules/fbx/fbx_document.cpp
@@ -2347,7 +2347,7 @@ PackedByteArray FBXDocument::generate_buffer(Ref<GLTFState> p_state) {
 	return PackedByteArray();
 }
 
-Error write_to_filesystem(Ref<GLTFState> p_state, const String &p_path) {
+Error FBXDocument::write_to_filesystem(Ref<GLTFState> p_state, const String &p_path) {
 	return ERR_UNAVAILABLE;
 }
 
diff --git a/modules/fbx/fbx_document.h b/modules/fbx/fbx_document.h
index ba48eb11aee1..c9256df4447c 100644
--- a/modules/fbx/fbx_document.h
+++ b/modules/fbx/fbx_document.h
@@ -53,14 +53,13 @@ public:
 	static String _gen_unique_name(HashSet<String> &unique_names, const String &p_name);
 
 public:
-	Error append_from_file(String p_path, Ref<GLTFState> p_state, uint32_t p_flags = 0, String p_base_path = String());
-	Error append_from_buffer(PackedByteArray p_bytes, String p_base_path, Ref<GLTFState> p_state, uint32_t p_flags = 0);
-	Error append_from_scene(Node *p_node, Ref<GLTFState> p_state, uint32_t p_flags = 0);
+	Error append_from_file(String p_path, Ref<GLTFState> p_state, uint32_t p_flags = 0, String p_base_path = String()) override;
+	Error append_from_buffer(PackedByteArray p_bytes, String p_base_path, Ref<GLTFState> p_state, uint32_t p_flags = 0) override;
+	Error append_from_scene(Node *p_node, Ref<GLTFState> p_state, uint32_t p_flags = 0) override;
 
-public:
-	Node *generate_scene(Ref<GLTFState> p_state, float p_bake_fps = 30.0f, bool p_trimming = false, bool p_remove_immutable_tracks = true);
-	PackedByteArray generate_buffer(Ref<GLTFState> p_state);
-	Error write_to_filesystem(Ref<GLTFState> p_state, const String &p_path);
+	Node *generate_scene(Ref<GLTFState> p_state, float p_bake_fps = 30.0f, bool p_trimming = false, bool p_remove_immutable_tracks = true) override;
+	PackedByteArray generate_buffer(Ref<GLTFState> p_state) override;
+	Error write_to_filesystem(Ref<GLTFState> p_state, const String &p_path) override;
 
 protected:
 	static void _bind_methods();
diff --git a/modules/gltf/gltf_document.h b/modules/gltf/gltf_document.h
index 1001b482cdf9..1901e89d5101 100644
--- a/modules/gltf/gltf_document.h
+++ b/modules/gltf/gltf_document.h
@@ -311,13 +311,13 @@ private:
 	static float get_max_component(const Color &p_color);
 
 public:
-	Error append_from_file(String p_path, Ref<GLTFState> p_state, uint32_t p_flags = 0, String p_base_path = String());
-	Error append_from_buffer(PackedByteArray p_bytes, String p_base_path, Ref<GLTFState> p_state, uint32_t p_flags = 0);
-	Error append_from_scene(Node *p_node, Ref<GLTFState> p_state, uint32_t p_flags = 0);
+	virtual Error append_from_file(String p_path, Ref<GLTFState> p_state, uint32_t p_flags = 0, String p_base_path = String());
+	virtual Error append_from_buffer(PackedByteArray p_bytes, String p_base_path, Ref<GLTFState> p_state, uint32_t p_flags = 0);
+	virtual Error append_from_scene(Node *p_node, Ref<GLTFState> p_state, uint32_t p_flags = 0);
 
-	Node *generate_scene(Ref<GLTFState> p_state, float p_bake_fps = 30.0f, bool p_trimming = false, bool p_remove_immutable_tracks = true);
-	PackedByteArray generate_buffer(Ref<GLTFState> p_state);
-	Error write_to_filesystem(Ref<GLTFState> p_state, const String &p_path);
+	virtual Node *generate_scene(Ref<GLTFState> p_state, float p_bake_fps = 30.0f, bool p_trimming = false, bool p_remove_immutable_tracks = true);
+	virtual PackedByteArray generate_buffer(Ref<GLTFState> p_state);
+	virtual Error write_to_filesystem(Ref<GLTFState> p_state, const String &p_path);
 
 public:
 	Error _parse_gltf_state(Ref<GLTFState> p_state, const String &p_search_path);