diff --git a/src/dutylog/application/bot/user_handlers.py b/src/dutylog/application/bot/user_handlers.py
index 5ec7a47..fa9a100 100644
--- a/src/dutylog/application/bot/user_handlers.py
+++ b/src/dutylog/application/bot/user_handlers.py
@@ -38,8 +38,8 @@ async def start_handler(
         last_name=message.from_user.last_name,
     )
 
-    if user and user.username != message.from_user.username:
-        await users_repository.update_user(user_id=message.from_user.id, username=message.from_user.id)
+    if user and user.username and user.username.strip().lower() != message.from_user.username.strip().lower():
+        await users_repository.update_user(user_id=message.from_user.id, username=message.from_user.username)
 
     is_creator = message.from_user.id == config.bot.creator_id
     is_admin = user.is_admin if user else False