diff --git a/tests/messages_tests/base.py b/tests/messages_tests/base.py
index 13158d7661..faf2713d79 100644
--- a/tests/messages_tests/base.py
+++ b/tests/messages_tests/base.py
@@ -60,7 +60,7 @@ class BaseTests:
                 },
             }],
             ROOT_URLCONF='messages_tests.urls',
-            MESSAGE_TAGS='',
+            MESSAGE_TAGS={},
             MESSAGE_STORAGE='%s.%s' % (self.storage_class.__module__, self.storage_class.__name__),
             SESSION_SERIALIZER='django.contrib.sessions.serializers.JSONSerializer',
         )