-#if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
- if(sa->sa.sa_family == AF_INET6)
- setsockopt(nfd, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
+#if defined(IPV6_V6ONLY)
+
+ if(sa->sa.sa_family == AF_INET6) {
+ setsockopt(nfd, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
+ }
+
+#else
+#warning IPV6_V6ONLY not defined