--- socket.c.orig
+++ socket.c
@@ -282,7 +282,7 @@ sock_hostname(struct host_info *host)
         return;
     }
 
-    if (STR_NE (host->name, res->ai_canonname) && STR_NE(host->name, "localhost"))
+    if ((!res->ai_canonname || STR_NE (host->name, res->ai_canonname)) && STR_NE(host->name, "localhost"))
     {
         /* We don't treat this as an error, though... */
         tcpd_warn("host name mismatch: %s != %s (%s)",