372,
     (375, 376),
     396,
+    401,
     900,
     903,
     904
    '372': _MsgParseExpectation(2),
    '376': _MsgParseExpectation(2),
    '396': _MsgParseExpectation(3),
+   '401': _MsgParseExpectation(3),
    '432': _MsgParseExpectation(3),
    '433': _MsgParseExpectation(3),
    '900': _MsgParseExpectation(4),
             # '@'-split because <https://defs.ircdocs.horse/defs/numerics>
             # claims: "<hostname> can also be in the form <user@hostname>"
             self._db.client_host = msg.params[1].split('@')[-1]
+        elif msg.match('401'):  # ERR_NOSUCHNICK
+            self._log(f'{msg.params[1]} not online', scope=LogScope.CHAT,
+                      target=msg.params[1], alert=True)
         elif msg.match('432'):  # ERR_ERRONEOUSNICKNAME
             alert = 'nickname refused for bad format'
             if msg.params[0] == '*':