diff --git a/telethon/telegram_client.py b/telethon/telegram_client.py
index f3a5ff1b..57d8b759 100644
--- a/telethon/telegram_client.py
+++ b/telethon/telegram_client.py
@@ -274,7 +274,7 @@ class TelegramClient(TelegramBareClient):
             for c in r.chats:
                 entities[c.id] = c
 
-            if isinstance(r, DialogsSlice):
+            if not isinstance(r, DialogsSlice):
                 # Don't enter next iteration if we already got all
                 break