diff --git a/traitlets/utils/bunch.py b/traitlets/utils/bunch.py
index 045dc88d..b1eb6c28 100644
--- a/traitlets/utils/bunch.py
+++ b/traitlets/utils/bunch.py
@@ -23,6 +23,7 @@ def __setattr__(self, key: str, value: Any) -> None:
         self.__setitem__(key, value)
 
     def __dir__(self) -> list[str]:
-        names = super().__dir__()
+        names: list[str] = []
+        names.extend(super().__dir__())
         names.extend(self.keys())
         return names