diff --git a/src/python/gem5/resources/resource.py b/src/python/gem5/resources/resource.py
index 0b9b12851a..b316f7dc9f 100644
--- a/src/python/gem5/resources/resource.py
+++ b/src/python/gem5/resources/resource.py
@@ -73,7 +73,7 @@ class CustomResource(AbstractResource):
     repository.
     """
 
-    def __init__(self, local_path: str, metadata: Optional[Dict] = None):
+    def __init__(self, local_path: str, metadata: Dict = {}):
         """
         :param local_path: The path of the resource on the host system.
         :param metadata: Add metadata for the custom resource.