diff --git a/telethon/network/mtprotosender.py b/telethon/network/mtprotosender.py
index eba0f51f..7f968197 100644
--- a/telethon/network/mtprotosender.py
+++ b/telethon/network/mtprotosender.py
@@ -266,8 +266,6 @@ class MTProtoSender:
                     state.future.cancel()
 
             self._pending_state.clear()
-            self._pending_ack.clear()
-            self._last_ack = None
             await helpers._cancel(
                 self._log,
                 send_loop_handle=self._send_loop_handle,