// Not a FIX, workaround for special case only!

--- a/sys/netinet6/in6.h
+++ b/sys/netinet6/in6.h
@@ -297,6 +297,8 @@ extern const struct in6_addr in6addr_linklocal_allv2routers;
        (((a)->s6_addr[0] == 0xfe) && (((a)->s6_addr[1] & 0xc0) == 0x80))
 #define IN6_IS_ADDR_SITELOCAL(a)       \
        (((a)->s6_addr[0] == 0xfe) && (((a)->s6_addr[1] & 0xc0) == 0xc0))
+#define IN6_IS_ADDR_ULA(a)     \
+       ((a)->s6_addr[0] == 0xfd)

 /*
  * Multicast
--- a/sys/netinet6/nd6_rtr.c
+++ b/sys/netinet6/nd6_rtr.c
@@ -1892,6 +1892,7 @@ pfxlist_onlink_check(void)
                LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
                        /* XXX: a link-local prefix should never be detached */
                        if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr) ||
+                            IN6_IS_ADDR_ULA(&pr->ndpr_prefix.sin6_addr) ||     /* FB: wild hack to avoid deletion of link routes for local provided prefix */
                            pr->ndpr_raf_onlink == 0 ||
                            pr->ndpr_raf_auto == 0)
                                continue;
@@ -1928,6 +1929,7 @@ pfxlist_onlink_check(void)
                int e;

                if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr) ||
+                    IN6_IS_ADDR_ULA(&pr->ndpr_prefix.sin6_addr) ||     /* FB: wild hack to avoid deletion of link routes for local provided prefix */
                    pr->ndpr_raf_onlink == 0 ||
                    pr->ndpr_raf_auto == 0)
                        continue;