diff --git a/tests/backend/mongodb/test_connection.py b/tests/backend/mongodb/test_connection.py
index a02b1735..e0b161b0 100644
--- a/tests/backend/mongodb/test_connection.py
+++ b/tests/backend/mongodb/test_connection.py
@@ -168,7 +168,7 @@ def test_initialize_replica_set(mock_cmd_line_opts):
         ]
 
         # check that it returns
-        assert initialize_replica_set('host', 1337, 1000, False, None, None) is None
+        assert initialize_replica_set('host', 1337, 1000, 'dbname', False, None, None) is None
 
     # test it raises OperationError if anything wrong
     with mock.patch.object(Database, 'command') as mock_command:
@@ -178,4 +178,4 @@ def test_initialize_replica_set(mock_cmd_line_opts):
         ]
 
         with pytest.raises(pymongo.errors.OperationFailure):
-            initialize_replica_set('host', 1337, 1000, False, None, None)
+            initialize_replica_set('host', 1337, 1000, 'dbname', False, None, None)