diff --git a/Utils.py b/Utils.py
index 0ff6682e8e30..ecc944e8f417 100644
--- a/Utils.py
+++ b/Utils.py
@@ -460,10 +460,10 @@ class KeyedDefaultDict(collections.defaultdict):
 
     def __init__(self,
                  default_factory: typing.Callable[[Any], Any] = None,
-                 default: typing.Union[typing.Mapping, typing.Iterable, None] = None,
+                 mapping: typing.Union[typing.Mapping, typing.Iterable, None] = None,
                  **kwargs):
-        if default is not None:
-            super().__init__(default_factory, default, **kwargs)
+        if mapping is not None:
+            super().__init__(default_factory, mapping, **kwargs)
         else:
             super().__init__(default_factory, **kwargs)