Index: src/zope/interface/interface.py
===================================================================
--- src/zope/interface/interface.py	(revision 121491)
+++ src/zope/interface/interface.py	(working copy)
@@ -434,7 +434,7 @@
     #implements(IInterface)
 
     def __init__(self, name, bases=(), attrs=None, __doc__=None,
-                 __module__=None):
+                 __module__=None, _frame=1):
 
         if attrs is None:
             attrs = {}
@@ -448,7 +448,7 @@
                     # Figure out what module defined the interface.
                     # This is how cPython figures out the module of
                     # a class, but of course it does it in C. :-/
-                    __module__ = sys._getframe(1).f_globals['__name__']
+                    __module__ = sys._getframe(_frame).f_globals['__name__']
                 except (AttributeError, KeyError):
                     pass