diff --git a/telethon/network/mtprotosender.py b/telethon/network/mtprotosender.py
index 7f9c8c82..4f33465f 100644
--- a/telethon/network/mtprotosender.py
+++ b/telethon/network/mtprotosender.py
@@ -543,6 +543,13 @@ class MTProtoSender:
             await self._process_message(message)
 
     async def _handle_update(self, message):
+        try:
+            assert message.obj.SUBCLASS_OF_ID == 0x8af52aac  # crc32(b'Updates')
+        except AssertionError:
+            self._log.warning('Note: %s is not an update, not dispatching it %s', message.obj)
+            return
+
+        print(message.obj.__class__.__name__)
         self._log.debug('Handling update %s', message.obj.__class__.__name__)
         if self._update_callback:
             self._update_callback(message.obj)