diff --git a/sys/netinet/ip_input.c b/sys/netinet/ip_input.c
index 1139e3a5abfa..733cc2901879 100644
--- a/sys/netinet/ip_input.c
+++ b/sys/netinet/ip_input.c
@@ -740,7 +740,10 @@ ip_input(struct mbuf *m)
 	}
 	if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
 		MROUTER_RLOCK();
-		/* Do not forward packets from IN_LINKLOCAL. */
+		/*
+		 * RFC 3927 2.7: Do not forward multicast packets from
+		 * IN_LINKLOCAL.
+		 */
 		if (V_ip_mrouter && !IN_LINKLOCAL(ntohl(ip->ip_src.s_addr))) {
 			/*
 			 * If we are acting as a multicast router, all
@@ -780,7 +783,7 @@ ip_input(struct mbuf *m)
 		goto ours;
 	if (ip->ip_dst.s_addr == INADDR_ANY)
 		goto ours;
-	/* Do not forward packets to or from IN_LINKLOCAL. */
+	/* RFC 3927 2.7: Do not forward packets to or from IN_LINKLOCAL. */
 	if (IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr)) ||
 	    IN_LINKLOCAL(ntohl(ip->ip_src.s_addr))) {
 		IPSTAT_INC(ips_cantforward);