diff --git a/tests/unit/test_fmha_v3_12w.py b/tests/unit/test_fmha_v3_12w.py
index 69a7ab33..1698e2d8 100644
--- a/tests/unit/test_fmha_v3_12w.py
+++ b/tests/unit/test_fmha_v3_12w.py
@@ -295,7 +295,7 @@ class FmhaV3:
 
 def test():
     torch.manual_seed(42)
-    for n in [128]:
+    for n in [128, 256]:
         m, hd = 128, HEAD_DIM
         q = torch.randn(m, hd, 1, dtype=torch.bfloat16, device='cuda')
         k = torch.randn(n, hd, 1, dtype=torch.bfloat16, device='cuda')