diff --git a/internlm/model/utils.py b/internlm/model/utils.py
index 48eb4b78..c6ae7002 100644
--- a/internlm/model/utils.py
+++ b/internlm/model/utils.py
@@ -603,7 +603,7 @@ def backward(ctx, grad_output, *args):
         if ctx.needs_input_grad[1]:
             if grad_weight_sync:
                 grad_weight_sync.wait()
-            if grad_bias and grad_bias_sync:
+            if grad_bias is not None and grad_bias_sync is not None:
                 grad_bias_sync.wait()
 
         return grad_input, grad_weight, grad_bias, None, None, None, None, None, None