diff --git a/telethon/client/chats.py b/telethon/client/chats.py
index 0823bf6a..91d0bd35 100644
--- a/telethon/client/chats.py
+++ b/telethon/client/chats.py
@@ -1000,7 +1000,7 @@ class ChatMethods:
 
         user = await self.get_input_entity(user)
         if isinstance(user, types.InputPeerSelf):
-            raise ValueError("You cannot restrict yourself")
+            raise ValueError('You cannot restrict yourself')
 
         if not isinstance(user, types.InputPeerUser):
             raise ValueError('You must pass a user entity')