diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 8254c40..d064790 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -340,7 +340,10 @@
     def tryProtocolCombo (server_protocol,
                           client_protocol,
                           expectedToWork,
-                          certsreqs=ssl.CERT_NONE):
+                          certsreqs=None):
+
+        if certsreqs == None:
+            certsreqs = ssl.CERT_NONE
 
         if certsreqs == ssl.CERT_NONE:
             certtype = "CERT_NONE"