diff --git a/shadowsocks/asyncdns.py b/shadowsocks/asyncdns.py
index 9713ec1..797704e 100644
--- a/shadowsocks/asyncdns.py
+++ b/shadowsocks/asyncdns.py
@@ -364,7 +364,7 @@ class DNSResolver(object):
                 callback((hostname, ip), error)
             else:
                 callback((hostname, None),
-                         Exception('unknown hostname %s' % hostname))
+                         Exception('unable to parse hostname %s' % hostname))
         if hostname in self._hostname_to_cb:
             del self._hostname_to_cb[hostname]
         if hostname in self._hostname_status:
diff --git a/shadowsocks/tcprelay.py b/shadowsocks/tcprelay.py
index 235505f..414bf43 100644
--- a/shadowsocks/tcprelay.py
+++ b/shadowsocks/tcprelay.py
@@ -587,7 +587,7 @@ class TCPRelayHandler(object):
                     # just trim VER CMD RSV
                     data = data[3:]
                 else:
-                    logging.error('unknown command %d', cmd)
+                    logging.error('invalid command %d', cmd)
                     self.destroy()
                     return