diff --git a/voluptuous/schema_builder.py b/voluptuous/schema_builder.py
index 8742810..dba71ba 100644
--- a/voluptuous/schema_builder.py
+++ b/voluptuous/schema_builder.py
@@ -1222,7 +1222,7 @@ def __init__(
         self,
         schema: Schemable,
         msg: typing.Optional[str] = None,
-        default=UNDEFINED,
+        default: typing.Any = UNDEFINED,
         description: typing.Optional[str] = None,
     ) -> None:
         super(Required, self).__init__(schema, msg=msg, description=description)