diff --git a/backend/open_webui/models/chats.py b/backend/open_webui/models/chats.py
index 0e1c6bef9d..7583f93429 100644
--- a/backend/open_webui/models/chats.py
+++ b/backend/open_webui/models/chats.py
@@ -1536,11 +1536,11 @@ class ChatTable:
         if not file_ids:
             return None
 
-        chat_message_file_ids = [
+        chat_message_file_ids = {
             item.id for item in await self.get_chat_files_by_chat_id_and_message_id(chat_id, message_id, db=db)
-        ]
+        }
         # Remove duplicates and existing file_ids
-        file_ids = list(set([file_id for file_id in file_ids if file_id and file_id not in chat_message_file_ids]))
+        file_ids = list({file_id for file_id in file_ids if file_id and file_id not in chat_message_file_ids})
         if not file_ids:
             return None