Index: gobject/propertyhelper.py
===================================================================
--- gobject/propertyhelper.py	(revisione 694)
+++ gobject/propertyhelper.py	(copia locale)
@@ -203,9 +203,7 @@
     def _check_default(self):
         ptype = self.type
         default = self.default
-        if (ptype == TYPE_BOOLEAN and
-            (default is not True or
-             default is not False)):
+        if (ptype == TYPE_BOOLEAN and (default not in (True, False))):
             raise TypeError(
                 "default must be True or False, not %r" % (default,))
         elif ptype == TYPE_PYOBJECT:
