diff --git a/python/sglang/multimodal_gen/runtime/layers/elementwise.py b/python/sglang/multimodal_gen/runtime/layers/elementwise.py
index 4c5e50857..16db42b90 100644
--- a/python/sglang/multimodal_gen/runtime/layers/elementwise.py
+++ b/python/sglang/multimodal_gen/runtime/layers/elementwise.py
@@ -23,7 +23,7 @@ class MulAdd(CustomOp):
             num_frames = b.shape[1]
             frame_seqlen = a.shape[1] // num_frames
             return c + (
-                a.unflatten(dim=1, sizes=(num_frames, frame_seqlen)) * b
+                a.unflatten(dim=1, sizes=(num_frames, frame_seqlen)) * (k + b)
             ).flatten(1, 2)
         else:
             # b.shape: [batch_size, 1, inner_dim]