diff --git a/setup.py b/setup.py
index c12a85358..8e8efdde7 100644
--- a/setup.py
+++ b/setup.py
@@ -369,7 +369,7 @@ def get_extensions():
                         exit()
 
             define_macros += [('MMCV_WITH_MLU', None)]
-            mlu_args = os.getenv('MMCV_MLU_ARGS')
+            mlu_args = os.getenv('MMCV_MLU_ARGS', '-DNDEBUG ')
             mluops_includes = []
             mluops_includes.append('-I' +
                                    os.path.abspath('./mlu-ops/bangc-ops'))