diff --git a/telethon/network/mtproto_sender.py b/telethon/network/mtproto_sender.py
index 01565251..ef02c05a 100644
--- a/telethon/network/mtproto_sender.py
+++ b/telethon/network/mtproto_sender.py
@@ -11,7 +11,7 @@ from ..errors import (
 from ..extensions import BinaryReader
 from ..tl import TLMessage, MessageContainer, GzipPacked
 from ..tl.all_tlobjects import tlobjects
-from ..tl.types import MsgsAck, Pong
+from ..tl.types import MsgsAck, Pong, BadServerSalt, BadMsgNotification
 from ..tl.functions.auth import LogOutRequest
 
 logging.getLogger(__name__).addHandler(logging.NullHandler())
@@ -180,24 +180,24 @@ class MtProtoSender:
         if code == 0xf35c6d01:  # rpc_result, (response of an RPC call)
             return self._handle_rpc_result(msg_id, sequence, reader)
 
-        if code == 0x347773c5:  # pong
+        if code == Pong.CONSTRUCTOR_ID:
             return self._handle_pong(msg_id, sequence, reader)
 
-        if code == 0x73f1f8dc:  # msg_container
+        if code == MessageContainer.CONSTRUCTOR_ID:
             return self._handle_container(msg_id, sequence, reader, state)
 
-        if code == 0x3072cfa1:  # gzip_packed
+        if code == GzipPacked.CONSTRUCTOR_ID:
             return self._handle_gzip_packed(msg_id, sequence, reader, state)
 
-        if code == 0xedab447b:  # bad_server_salt
+        if code == BadServerSalt.CONSTRUCTOR_ID:
             return self._handle_bad_server_salt(msg_id, sequence, reader)
 
-        if code == 0xa7eff811:  # bad_msg_notification
+        if code == BadMsgNotification.CONSTRUCTOR_ID:
             return self._handle_bad_msg_notification(msg_id, sequence, reader)
 
-        # msgs_ack, it may handle the request we wanted
-        if code == 0x62d6b459:
+        if code == MsgsAck.CONSTRUCTOR_ID:  # may handle the request we wanted
             ack = reader.tgread_object()
+            assert isinstance(ack, MsgsAck)
             # Ignore every ack request *unless* when logging out, when it's
             # when it seems to only make sense. We also need to set a non-None
             # result since Telegram doesn't send the response for these.
@@ -219,7 +219,12 @@ class MtProtoSender:
 
             return True
 
-        self._logger.debug('Unknown message: {}'.format(hex(code)))
+        self._logger.debug(
+            '[WARN] Unknown message: {}, data left in the buffer: {}'
+            .format(
+                hex(code), repr(reader.get_bytes()[reader.tell_position():])
+            )
+        )
         return False
 
     # endregion
@@ -279,14 +284,15 @@ class MtProtoSender:
 
     def _handle_bad_server_salt(self, msg_id, sequence, reader):
         self._logger.debug('Handling bad server salt')
-        reader.read_int(signed=False)  # code
-        bad_msg_id = reader.read_long()
-        reader.read_int()  # bad_msg_seq_no
-        reader.read_int()  # error_code
-        new_salt = reader.read_long(signed=False)
-        self.session.salt = new_salt
+        bad_salt = reader.tgread_object()
+        assert isinstance(bad_salt, BadServerSalt)
 
-        request = self._pop_request(bad_msg_id)
+        # Our salt is unsigned, but the objects work with signed salts
+        self.session.salt = struct.unpack(
+            '<Q', struct.pack('<q', bad_salt.new_server_salt)
+        )[0]
+
+        request = self._pop_request(bad_salt.bad_msg_id)
         if request:
             self.send(request)
 
@@ -294,25 +300,23 @@ class MtProtoSender:
 
     def _handle_bad_msg_notification(self, msg_id, sequence, reader):
         self._logger.debug('Handling bad message notification')
-        reader.read_int(signed=False)  # code
-        reader.read_long()  # request_id
-        reader.read_int()  # request_sequence
+        bad_msg = reader.tgread_object()
+        assert isinstance(bad_msg, BadMsgNotification)
 
-        error_code = reader.read_int()
-        error = BadMessageError(error_code)
-        if error_code in (16, 17):
+        error = BadMessageError(bad_msg.error_code)
+        if bad_msg.error_code in (16, 17):
             # sent msg_id too low or too high (respectively).
             # Use the current msg_id to determine the right time offset.
             self.session.update_time_offset(correct_msg_id=msg_id)
             self._logger.debug('Read Bad Message error: ' + str(error))
             self._logger.debug('Attempting to use the correct time offset.')
             return True
-        elif error_code == 32:
+        elif bad_msg.error_code == 32:
             # msg_seqno too low, so just pump it up by some "large" amount
             # TODO A better fix would be to start with a new fresh session ID
             self.session._sequence += 64
             return True
-        elif error_code == 33:
+        elif bad_msg.error_code == 33:
             # msg_seqno too high never seems to happen but just in case
             self.session._sequence -= 16
             return True
diff --git a/telethon/tl/gzip_packed.py b/telethon/tl/gzip_packed.py
index 05453d4b..a7d09188 100644
--- a/telethon/tl/gzip_packed.py
+++ b/telethon/tl/gzip_packed.py
@@ -34,5 +34,5 @@ class GzipPacked(TLObject):
 
     @staticmethod
     def read(reader):
-        reader.read_int(signed=False)  # code
+        assert reader.read_int(signed=False) == GzipPacked.CONSTRUCTOR_ID
         return gzip.decompress(reader.tgread_bytes())