diff --git a/freecad/gears/features.py b/freecad/gears/features.py
index 60558cc..627b157 100644
--- a/freecad/gears/features.py
+++ b/freecad/gears/features.py
@@ -83,7 +83,10 @@ class BaseGear(object):
         # Needed to make this object "attachable",
         # aka able to attach parameterically to other objects
         # cf. https://wiki.freecadweb.org/Scripted_objects_with_attachment
-        obj.addExtension('Part::AttachExtensionPython', obj)
+        if int(App.Version()[1]) >= 20:
+            obj.addExtension('Part::AttachExtensionPython')
+        else:
+            obj.addExtension('Part::AttachExtensionPython', obj)
 
     def execute(self, fp):
         # checksbackwardcompatibility: