diff --git a/nest/rt-attr.c b/nest/rt-attr.c
index 3db55202..13262b45 100644
--- a/nest/rt-attr.c
+++ b/nest/rt-attr.c
@@ -234,6 +234,11 @@ mpnh_compare_node(struct mpnh *x, struct mpnh *y)
   if (r)
     return r;
 
+  if (!x->iface)
+    return 1;
+  if (!y->iface)
+    return -1;
+
   return ((int) x->iface->index) - ((int) y->iface->index);
 }