diff --git a/utils.py b/utils.py
index ff46385..2195af3 100644
--- a/utils.py
+++ b/utils.py
@@ -276,6 +276,7 @@ def upload_image(image_path, file_name=None):
             file_extension = os.path.splitext(image_path)[1]
             object_key = f'dotabot/{timestamp}_{random_id}{file_extension}'
         else:
+            file_extension = os.path.splitext(file_name)[1]
             object_key = f'dotabot/{file_name}'
         
         # 设置文件的Content-Type