diff --git a/tarn/location/disk_dict/config.py b/tarn/location/disk_dict/config.py
index 36df9b6..c852621 100644
--- a/tarn/location/disk_dict/config.py
+++ b/tarn/location/disk_dict/config.py
@@ -52,13 +52,7 @@ def build(self):
 class ToolConfig(NoExtra):
     name: str
     args: Tuple = ()
-    kwargs: Optional[Dict[str, Any]] = Field(None, validate_default=True)
-
-    @field_validator('kwargs', always=True)
-    def normalize_kwargs(cls, v):
-        if v is None:
-            return {}
-        return v
+    kwargs: Optional[Dict[str, Any]] = Field(None, default_factory=dict)
 
 
 class StorageConfig(NoExtra):