diff --git a/python/llm/src/ipex_llm/transformers/models/bert.py b/python/llm/src/ipex_llm/transformers/models/bert.py
index 2f1c4f56..95002c06 100644
--- a/python/llm/src/ipex_llm/transformers/models/bert.py
+++ b/python/llm/src/ipex_llm/transformers/models/bert.py
@@ -119,7 +119,7 @@ def encoder_forward(
     output_hidden_states: Optional[bool] = False,
     return_dict: Optional[bool] = True,
 ):
-    if attention_mask and not attention_mask.any():
+    if attention_mask is not None and not attention_mask.any():
         attention_mask = None
     return BertEncoder.forward(
         self=self,