diff --git a/sys/netinet6/in6_var.h b/sys/netinet6/in6_var.h
--- a/sys/netinet6/in6_var.h
+++ b/sys/netinet6/in6_var.h
@@ -323,8 +323,7 @@
 	struct prf_ra {
 		u_char onlink : 1;
 		u_char autonomous : 1;
-		u_char ra_derived: 1;
-		u_char reserved : 5;
+		u_char reserved : 6;
 	} prf_ra;
 	u_char prf_reserved1;
 	u_short prf_reserved2;
@@ -355,7 +354,6 @@
 
 #define ipr_raf_onlink		ipr_flags.prf_ra.onlink
 #define ipr_raf_auto		ipr_flags.prf_ra.autonomous
-#define ipr_raf_ra_derived	ipr_flags.prf_ra.ra_derived
 
 #define ipr_statef_onlink	ipr_flags.prf_state.onlink
 
diff --git a/sys/netinet6/nd6.h b/sys/netinet6/nd6.h
--- a/sys/netinet6/nd6.h
+++ b/sys/netinet6/nd6.h
@@ -242,7 +242,6 @@
 #define ndpr_raf		ndpr_flags
 #define ndpr_raf_onlink		ndpr_flags.onlink
 #define ndpr_raf_auto		ndpr_flags.autonomous
-#define ndpr_raf_ra_derived	ndpr_flags.ra_derived
 #define ndpr_raf_router		ndpr_flags.router
 
 struct nd_pfxrouter {
diff --git a/sys/netinet6/nd6.c b/sys/netinet6/nd6.c
--- a/sys/netinet6/nd6.c
+++ b/sys/netinet6/nd6.c
@@ -84,11 +84,13 @@
 
 #include <security/mac/mac_framework.h>
 
+#define	ND6_PREFIX_FROM_ROUTER(pr) \
+	(!LIST_EMPTY(&(pr)->ndpr_advrtrs) || \
+	 ((pr)->ndpr_stateflags & NDPRF_DETACHED) == NDPRF_DETACHED)
+
 #define ND6_SLOWTIMER_INTERVAL (60 * 60) /* 1 hour */
 #define ND6_RECALC_REACHTM_INTERVAL (60 * 120) /* 2 hours */
 
-#define SIN6(s) ((const struct sockaddr_in6 *)(s))
-
 MALLOC_DEFINE(M_IP6NDP, "ip6ndp", "IPv6 Neighbor Discovery");
 
 VNET_DEFINE_STATIC(int, nd6_prune) = 1;
@@ -1800,7 +1802,7 @@
 
 		ND6_WLOCK();
 		LIST_FOREACH_SAFE(pr, &V_nd_prefix, ndpr_entry, next) {
-			if (pr->ndpr_raf_ra_derived)
+			if (ND6_PREFIX_FROM_ROUTER(pr))
 				nd6_prefix_unlink(pr, &prl);
 		}
 		ND6_WUNLOCK();
@@ -2678,8 +2680,6 @@
 
 	ND6_RLOCK();
 	LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
-		if (!pr->ndpr_raf_ra_derived)
-			continue;
 		p.prefix = pr->ndpr_prefix;
 		if (sa6_recoverscope(&p.prefix)) {
 			log(LOG_ERR, "scope error in prefix list (%s)\n",
diff --git a/sys/netinet6/nd6_rtr.c b/sys/netinet6/nd6_rtr.c
--- a/sys/netinet6/nd6_rtr.c
+++ b/sys/netinet6/nd6_rtr.c
@@ -520,7 +520,6 @@
 			    ND_OPT_PI_FLAG_ONLINK) ? 1 : 0;
 			pr.ndpr_raf_auto = (pi->nd_opt_pi_flags_reserved &
 			    ND_OPT_PI_FLAG_AUTO) ? 1 : 0;
-			pr.ndpr_raf_ra_derived = 1;
 			pr.ndpr_plen = pi->nd_opt_pi_prefix_len;
 			pr.ndpr_vltime = ntohl(pi->nd_opt_pi_valid_time);
 			pr.ndpr_pltime = ntohl(pi->nd_opt_pi_preferred_time);