Index: sys/netinet6/in6.c
===================================================================
--- sys/netinet6/in6.c
+++ sys/netinet6/in6.c
@@ -627,6 +627,7 @@
 		 * later advertised RAs (when accept_rtadv is non 0), which is
 		 * an intended behavior.
 		 */
+		pr0.ndpr_raf_manual = 1; /* mark as manually-configured */
 		pr0.ndpr_raf_onlink = 1; /* should be configurable? */
 		pr0.ndpr_raf_auto =
 		    ((ifra->ifra_flags & IN6_IFF_AUTOCONF) != 0);
Index: sys/netinet6/in6_var.h
===================================================================
--- sys/netinet6/in6_var.h
+++ sys/netinet6/in6_var.h
@@ -326,7 +326,8 @@
 	struct prf_ra {
 		u_char onlink : 1;
 		u_char autonomous : 1;
-		u_char reserved : 6;
+		u_char manual: 1;
+		u_char reserved : 5;
 	} prf_ra;
 	u_char prf_reserved1;
 	u_short prf_reserved2;
@@ -357,6 +358,7 @@
 
 #define ipr_raf_onlink		ipr_flags.prf_ra.onlink
 #define ipr_raf_auto		ipr_flags.prf_ra.autonomous
+#define ipr_raf_manual		ipr_flags.prf_ra.manual
 
 #define ipr_statef_onlink	ipr_flags.prf_state.onlink
 
Index: sys/netinet6/nd6.h
===================================================================
--- sys/netinet6/nd6.h
+++ sys/netinet6/nd6.h
@@ -170,6 +170,7 @@
 /* Prefix status */
 #define NDPRF_ONLINK		0x1
 #define NDPRF_DETACHED		0x2
+#define	NDPRF_MANUAL		0x4
 
 /* protocol constants */
 #define MAX_RTR_SOLICITATION_DELAY	1	/* 1sec */
@@ -243,6 +244,7 @@
 #define ndpr_raf		ndpr_flags
 #define ndpr_raf_onlink		ndpr_flags.onlink
 #define ndpr_raf_auto		ndpr_flags.autonomous
+#define ndpr_raf_manual		ndpr_flags.manual
 #define ndpr_raf_router		ndpr_flags.router
 
 struct nd_pfxrouter {
Index: sys/netinet6/nd6.c
===================================================================
--- sys/netinet6/nd6.c
+++ sys/netinet6/nd6.c
@@ -1788,6 +1788,8 @@
 		LIST_FOREACH_SAFE(pr, &V_nd_prefix, ndpr_entry, next) {
 			if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr))
 				continue; /* XXX */
+			if (pr->ndpr_raf_manual)
+				continue; /* Skip manually-configured prefixes */
 			nd6_prefix_unlink(pr, &prl);
 		}
 		ND6_WUNLOCK();