diff --git a/core/net/rpl/rpl-dag.c b/core/net/rpl/rpl-dag.c
index baad9946b..bc624cf85 100644
--- a/core/net/rpl/rpl-dag.c
+++ b/core/net/rpl/rpl-dag.c
@@ -703,7 +703,9 @@ rpl_remove_parent(rpl_dag_t *dag, rpl_parent_t *parent)
 void
 rpl_nullify_parent(rpl_dag_t *dag, rpl_parent_t *parent)
 {
-  if(parent == dag->preferred_parent) {
+  /* This function can be called when the preferred parent is NULL, so we
+     need to handle this condition in order to trigger uip_ds6_defrt_rm. */
+  if(parent == dag->preferred_parent || dag->preferred_parent == NULL) {
     dag->preferred_parent = NULL;
     dag->rank = INFINITE_RANK;
     if(dag->joined) {