diff --git a/python/sglang/srt/distributed/parallel_state.py b/python/sglang/srt/distributed/parallel_state.py
index c572fc8e8..c507f4701 100644
--- a/python/sglang/srt/distributed/parallel_state.py
+++ b/python/sglang/srt/distributed/parallel_state.py
@@ -156,7 +156,7 @@ if supports_custom_op():
     direct_register_custom_op(
         op_name="reg_all_gather_into_tensor",
         op_func=reg_all_gather_into_tensor,
-        mutates_args=[],
+        mutates_args=["output"],
         fake_impl=reg_all_gather_into_tensor_fake,
     )