diff --git a/tests/unit/test_fmha_v3_stage_c.py b/tests/unit/test_fmha_v3_stage_c.py
index 9f638dda..681b9cdd 100644
--- a/tests/unit/test_fmha_v3_stage_c.py
+++ b/tests/unit/test_fmha_v3_stage_c.py
@@ -423,6 +423,8 @@ class FmhaV3StageCMulti:
 
 
 def test():
+    import os
+    os.environ['CUDA_LAUNCH_BLOCKING'] = '1'
     torch.manual_seed(42)
     for n in [128]:
         torch.manual_seed(42)