diff --git a/litellm/types/router.py b/litellm/types/router.py
index 39eaf6994a3..ee6dd95c0c3 100644
--- a/litellm/types/router.py
+++ b/litellm/types/router.py
@@ -25,7 +25,7 @@ def get_model_config(arbitrary_types_allowed: bool = False) -> ConfigDict:
     else:
         from pydantic import Extra
 
-        model_config = ConfigDict(extra=Extra.allow)  # type: ignore
+        model_config = ConfigDict(extra=Extra.allow, arbitrary_types_allowed=arbitrary_types_allowed)  # type: ignore
 
     return model_config