diff --git a/lib/hawat/test/__init__.py b/lib/hawat/test/__init__.py
index 0bbf8c91346a83cf8e66f18a3a37234b12cb0365..95b0c8ecd2e04bdff21e276a3eb58ed6e894d576 100644
--- a/lib/hawat/test/__init__.py
+++ b/lib/hawat/test/__init__.py
@@ -467,7 +467,7 @@ class RegistrationHawatTestCase(HawatTestCase):
         'timezone': None
     }
 
-    def assertRegisterFail(self, url, data, environ_base = None):  # pylint: disable=locally-disabled,invalid-name
+    def assertRegisterFail(self, url, data, environ_base = {}):  # pylint: disable=locally-disabled,invalid-name
         response = response = self.client.get(
             url,
             follow_redirects = True,
@@ -506,7 +506,7 @@ class RegistrationHawatTestCase(HawatTestCase):
         )
 
 
-    def assertRegister(self, url, data, emails, environ_base = None):  # pylint: disable=locally-disabled,invalid-name
+    def assertRegister(self, url, data, emails, environ_base = {}):  # pylint: disable=locally-disabled,invalid-name
         uname = 'test'
         self.mailbox_monitoring('on')