diff --git a/python/tvm/script/tir/__init__.pyi b/python/tvm/script/tir/__init__.pyi
index 4c3b7226a6f1..7b7213526778 100644
--- a/python/tvm/script/tir/__init__.pyi
+++ b/python/tvm/script/tir/__init__.pyi
@@ -364,13 +364,13 @@ def unroll(
 def thread_binding(
     begin: Union[PrimExpr, int],
     end: Union[PrimExpr, int],
-    thread: str = None,
+    thread: str,
     annotations: Optional[Mapping[str, Object]] = None,
 ) -> Iterable[IterVar]: ...
 @overload
 def thread_binding(
     end: Union[PrimExpr, int],
-    thread: str = None,
+    thread: str,
     annotations: Optional[Mapping[str, Object]] = None,
 ) -> Iterable[IterVar]: ...
 @overload