diff --git a/third_party/paddle_audio/frontend/common.py b/third_party/paddle_audio/frontend/common.py
index aa7ea62c5f06f97c201525747393087df8a7e001..7638dae5335698483611ae7cedd13fd4aa718c5c 100644
--- a/third_party/paddle_audio/frontend/common.py
+++ b/third_party/paddle_audio/frontend/common.py
@@ -1,6 +1,6 @@
 import paddle
 import numpy as np
-from typing import Tuple, Optional
+from typing import Tuple, Optional, Union
 
 
 # https://github.com/kaldi-asr/kaldi/blob/cbed4ff688/src/feat/feature-window.cc#L109