ospf6d part of 6Wind patch.
diff --git a/ospf6d/ospf6_top.c b/ospf6d/ospf6_top.c
index a8a058f..f9cc329 100644
--- a/ospf6d/ospf6_top.c
+++ b/ospf6d/ospf6_top.c
@@ -286,6 +286,9 @@
 void
 ospf6_delete (struct ospf6 *ospf6)
 {
+  if (!ospf6)
+    return;
+
   ospf6_route_remove_all (ospf6->route_table);
   ospf6_free (ospf6);
 }