diff --git a/ospfd/ospf_nsm.c b/ospfd/ospf_nsm.c
index 279d2a0..cbc3171 100644
--- a/ospfd/ospf_nsm.c
+++ b/ospfd/ospf_nsm.c
@@ -216,7 +216,7 @@
     {
     case OSPF_OPAQUE_LINK_LSA:
       /* Exclude type-9 LSAs that does not have the same "oi" with "nbr". */
-      if (lsa->oi != nbr->oi)
+      if (nbr->oi && ospf_if_exists (lsa->oi) != nbr->oi)
           return 0;
       break;
     case OSPF_OPAQUE_AREA_LSA: