diff --git a/github/tests/AuthenticatedUser.py b/github/tests/AuthenticatedUser.py
index bb00ccc7..e108975d 100644
--- a/github/tests/AuthenticatedUser.py
+++ b/github/tests/AuthenticatedUser.py
@@ -236,4 +236,4 @@ class AuthenticatedUser(Framework.TestCase):
         self.assertListKeyEqual(self.user.get_teams(), lambda t: t.name, ["Owners", "Honoraries", "Honoraries", "Honoraries", "Honoraries", "Honoraries", "Honoraries", "Honoraries", "Honoraries", "Honoraries"])
 
     def testAcceptInvitation(self):
-        self.assertIsNone(self.user.accept_invitation(4294886))
\ No newline at end of file
+        self.assertEqual(self.user.accept_invitation(4294886), None)