diff --git a/telethon/network/mtprotosender.py b/telethon/network/mtprotosender.py
index 556d0a7f..c2e1dc36 100644
--- a/telethon/network/mtprotosender.py
+++ b/telethon/network/mtprotosender.py
@@ -373,12 +373,12 @@ class MTProtoSender:
                 # TODO there should probably only be one place to except all these errors
                 if isinstance(e, InvalidBufferError) and e.code == 404:
                     self._log.info('Broken authorization key; resetting')
+                    self.auth_key.key = None
+                    if self._auth_key_callback:
+                        self._auth_key_callback(None)
                 else:
                     self._log.warning('Invalid buffer %s', e)
 
-                self.auth_key.key = None
-                if self._auth_key_callback:
-                    self._auth_key_callback(None)
             except Exception as e:
                 last_error = e
                 self._log.exception('Unexpected exception reconnecting on '
@@ -497,13 +497,12 @@ class MTProtoSender:
             except BufferError as e:
                 if isinstance(e, InvalidBufferError) and e.code == 404:
                     self._log.info('Broken authorization key; resetting')
+                    self.auth_key.key = None
+                    if self._auth_key_callback:
+                        self._auth_key_callback(None)
                 else:
                     self._log.warning('Invalid buffer %s', e)
 
-                self.auth_key.key = None
-                if self._auth_key_callback:
-                    self._auth_key_callback(None)
-
                 self._start_reconnect(e)
                 return
             except Exception as e: