diff --git a/src/supertux/game_object_manager.cpp b/src/supertux/game_object_manager.cpp
index e74d839ea4..d53ba29af9 100644
--- a/src/supertux/game_object_manager.cpp
+++ b/src/supertux/game_object_manager.cpp
@@ -808,7 +808,8 @@ GameObjectManager::register_class(ssq::VM& vm)
   cls.addFunc("get_ambient_blue", &GameObjectManager::get_ambient_blue);
   cls.addFunc("set_music", &GameObjectManager::set_music);
   cls.addFunc<void, GameObjectManager, const std::string&, const std::string&,
-              float, float, const std::string&, const std::string&>("add_object", &GameObjectManager::add_object);
+              float, float, const std::string&, const std::string&>("add_object",
+                &GameObjectManager::add_object, ssq::DefaultArguments<const std::string&, const std::string&>("auto", ""));
 }
 
 /* EOF */
diff --git a/src/supertux/game_object_manager.hpp b/src/supertux/game_object_manager.hpp
index 18b70ce604..d335f55192 100644
--- a/src/supertux/game_object_manager.hpp
+++ b/src/supertux/game_object_manager.hpp
@@ -138,8 +138,8 @@ class GameObjectManager : public ExposableClass
    * @param string $data Additional data in S-Expression format (check object definitions in level files).
    */
   void add_object(const std::string& class_name, const std::string& name,
-                  float pos_x, float pos_y, const std::string& direction,
-                  const std::string& data);
+                  float pos_x, float pos_y, const std::string& direction = "auto",
+                  const std::string& data = "");
 
   float get_width() const;
   float get_height() const;