--- gi/overrides/Gio.py.old	2011-03-09 02:34:55.000000000 +0300
+++ gi/overrides/Gio.py	2011-03-09 02:35:39.000000000 +0300
@@ -119,8 +119,11 @@
 
         result_callback(obj, self._unpack_result(ret), real_user_data)
 
-    def __call__(self, signature, *args, **kwargs):
-        arg_variant = GLib.Variant(signature, tuple(args))
+    def __call__(self, signature=None, *args, **kwargs):
+        if signature:
+            arg_variant = GLib.Variant(signature, tuple(args))
+        else:
+            arg_variant = None
 
         if 'result_handler' in kwargs:
             # asynchronous call
