diff --git a/unsloth_zoo/temporary_patches/utils.py b/unsloth_zoo/temporary_patches/utils.py
index b35ecac7b..97a6ed58e 100644
--- a/unsloth_zoo/temporary_patches/utils.py
+++ b/unsloth_zoo/temporary_patches/utils.py
@@ -292,6 +292,9 @@ def _canonicalize_annotation(annotation: Any) -> Any:
         if origin is not None:
             args = t.get_args(annotation)
             args = tuple(canonicalize_annotation(arg) for arg in args)
+            # Map origin to canonical form (e.g., types.UnionType -> typing.Union)
+            # so that `int | str` and `Union[int, str]` are equivalent
+            origin = TYPE_MAPPINGS.get(origin, origin)
             return (origin, args)
     return TYPE_MAPPINGS.get(annotation, annotation)
 pass