diff --git a/lib/route/tc.c b/lib/route/tc.c
index fbc5c7e..0886e8e 100644
--- a/lib/route/tc.c
+++ b/lib/route/tc.c
@@ -300,6 +300,8 @@ void rtnl_tc_set_link(struct rtnl_tc *tc, struct rtnl_link *link)
 
 	if (!link)
 		return;
+	if (!link->l_index)
+		BUG();
 
 	nl_object_get(OBJ_CAST(link));
 	tc->tc_link = link;