diff --git a/tokenization_chatglm.py b/tokenization_chatglm.py
index aedbcbe..5f594e6 100644
--- a/tokenization_chatglm.py
+++ b/tokenization_chatglm.py
@@ -299,7 +299,7 @@ class ChatGLMTokenizer(PreTrainedTokenizer):
         """
         if os.path.isdir(save_directory):
             vocab_file = os.path.join(
-                save_directory, VOCAB_FILES_NAMES["vocab_file"]
+                save_directory, self.vocab_files_names["vocab_file"]
             )
         else:
             vocab_file = save_directory