diff --git a/vllm/model_executor/layers/fusion/mm_input_norm.py b/vllm/model_executor/layers/fusion/mm_input_norm.py
index ea1dd1da22..a21828033d 100644
--- a/vllm/model_executor/layers/fusion/mm_input_norm.py
+++ b/vllm/model_executor/layers/fusion/mm_input_norm.py
@@ -71,7 +71,7 @@ def fused_mm_input_norm_triton(
     outputs: torch.Tensor,
     weight: torch.Tensor,
     bias: torch.Tensor,
-):
+) -> torch.Tensor:
     """Fused per-channel affine transform for normalisation.
 
     Args: