diff --git a/django/contrib/auth/backends.py b/django/contrib/auth/backends.py
index be6cfede11..f79929e2d2 100644
--- a/django/contrib/auth/backends.py
+++ b/django/contrib/auth/backends.py
@@ -1,6 +1,11 @@
 from django.db import connection
 from django.contrib.auth.models import User
 
+try: 
+    set 
+except NameError: 
+    from sets import Set as set # Python 2.3 fallback
+ 	
 class ModelBackend:
     """
     Authenticate against django.contrib.auth.models.User