diff --git a/Lib/test/test_multibytecodec_support.py b/Lib/test/test_multibytecodec_support.py
index 1631e46e397bcf..1237881cad3c1c 100644
--- a/Lib/test/test_multibytecodec_support.py
+++ b/Lib/test/test_multibytecodec_support.py
@@ -256,7 +256,7 @@ def test_streamwriter(self):
 
                 self.assertEqual(ostream.getvalue(), self.tstring[0])
 
-class TestBase_Mapping(unittest.TestCase):
+class TestBase_Mapping(object):
     pass_enctest = []
     pass_dectest = []
     supmaps = []