diff --git a/tests/unit/config/test_configtypes.py b/tests/unit/config/test_configtypes.py
index c77701f0d..219519638 100644
--- a/tests/unit/config/test_configtypes.py
+++ b/tests/unit/config/test_configtypes.py
@@ -249,9 +249,8 @@ class BadMappingSubclass(configtypes.MappingType):
     }
 
     def __init__(self, none_ok=False):
-        super().__init__(
-            none_ok,
-            valid_values = configtypes.ValidValues('one', 'two'))
+        super().__init__(none_ok)
+        self.valid_values = configtypes.ValidValues('one', 'two'))
 
 
 class TestMappingType: