diff --git a/libs/lib/xaal/lib/tools.py b/libs/lib/xaal/lib/tools.py
index e7c59738cd0654dfa13f9453e3c7c16a68b66fdc..2c46feb7d2cf3f15cb05776a8e9346f3f84ccb38 100644
--- a/libs/lib/xaal/lib/tools.py
+++ b/libs/lib/xaal/lib/tools.py
@@ -101,11 +101,11 @@ def bytes_to_uuid(val: bytes) -> Optional[UUID]:
         return None
 
 
-def is_valid_uuid(val: Union[UUID, str]) -> bool:
+def is_valid_uuid(val: UUID) -> bool:
     return isinstance(val, UUID)
 
 
-def is_valid_address(val: Union[UUID, str]) -> bool:
+def is_valid_address(val: UUID) -> bool:
     return is_valid_uuid(val)