diff --git a/fastNLP/io/file_utils.py b/fastNLP/io/file_utils.py
index a0bfa88a..ff33872b 100644
--- a/fastNLP/io/file_utils.py
+++ b/fastNLP/io/file_utils.py
@@ -557,4 +557,4 @@ def _get_file_name_base_on_postfix(dir_path, postfix):
         raise FileNotFoundError(f"There is no file endswith {postfix} file in {dir_path}")
     elif len(files) > 1:
         raise FileExistsError(f"There are multiple *{postfix} files in {dir_path}")
-    return os.path.join(dir_path, files[0])
\ No newline at end of file
+    return os.path.join(dir_path, files[0])
diff --git a/fastNLP/modules/encoder/bert.py b/fastNLP/modules/encoder/bert.py
index da9cc6d6..4e8d644f 100644
--- a/fastNLP/modules/encoder/bert.py
+++ b/fastNLP/modules/encoder/bert.py
@@ -15,7 +15,7 @@ import torch
 from torch import nn
 import numpy as np
 
-from fastNLP.io.file_utils import _get_file_name_base_on_postfix
+from ...io.file_utils import _get_file_name_base_on_postfix
 from ...io.file_utils import _get_bert_dir
 from ...core import logger