diff --git a/src/dhcp6.c b/src/dhcp6.c
index 3956ff1..cf613ad 100644
--- a/src/dhcp6.c
+++ b/src/dhcp6.c
@@ -33,12 +33,12 @@ void dhcp6_init(void)
 {
   int fd;
   struct sockaddr_in6 saddr;
-#if defined(IP_TOS) && defined(IPTOS_CLASS_CS6)
+#if defined(IPV6_TCLASS) && defined(IPTOS_CLASS_CS6)
   int class = IPTOS_CLASS_CS6;
 #endif
   
   if ((fd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP)) == -1 ||
-#if defined(IP_TOS) && defined(IPTOS_CLASS_CS6)
+#if defined(IPV6_TCLASS) && defined(IPTOS_CLASS_CS6)
       setsockopt(fd, IPPROTO_IPV6, IPV6_TCLASS, &class, sizeof(class)) == -1 ||
 #endif
       !fix_fd(fd) ||
diff --git a/src/radv.c b/src/radv.c
index a413c09..87efc4e 100644
--- a/src/radv.c
+++ b/src/radv.c
@@ -50,7 +50,7 @@ void ra_init(time_t now)
 {
   struct icmp6_filter filter;
   int fd;
-#if defined(IP_TOS) && defined(IPTOS_CLASS_CS6)
+#if defined(IPV6_TCLASS) && defined(IPTOS_CLASS_CS6)
   int class = IPTOS_CLASS_CS6;
 #endif
   int val = 255; /* radvd uses this value */
@@ -72,7 +72,7 @@ void ra_init(time_t now)
   
   if ((fd = socket(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) == -1 ||
       getsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &hop_limit, &len) ||
-#if defined(IP_TOS) && defined(IPTOS_CLASS_CS6)
+#if defined(IPV6_TCLASS) && defined(IPTOS_CLASS_CS6)
       setsockopt(fd, IPPROTO_IPV6, IPV6_TCLASS, &class, sizeof(class)) == -1 ||
 #endif
       !fix_fd(fd) ||