diff --git a/sys/include/net/gnrc/rpl/dodag.h b/sys/include/net/gnrc/rpl/dodag.h
index 275572688074c963c66cd1d87c70e3fea099cff4..e46a5e14e54afbc7722b68d02cd0ee42c6d009db 100644
--- a/sys/include/net/gnrc/rpl/dodag.h
+++ b/sys/include/net/gnrc/rpl/dodag.h
@@ -192,16 +192,6 @@ gnrc_rpl_parent_t *gnrc_rpl_parent_get(gnrc_rpl_dodag_t *dodag, ipv6_addr_t *add
  */
 void gnrc_rpl_parent_update(gnrc_rpl_dodag_t *dodag, gnrc_rpl_parent_t *parent);
 
-/**
- * @brief   Find the parent with the lowest rank and update the DODAG's preferred parent
- *
- * @param[in] dodag     Pointer to the DODAG
- *
- * @return  Pointer to the preferred parent, on success.
- * @return  NULL, otherwise.
- */
-gnrc_rpl_parent_t *gnrc_rpl_find_preferred_parent(gnrc_rpl_dodag_t *dodag);
-
 /**
  * @brief   Start a local repair.
  *
diff --git a/sys/net/gnrc/routing/rpl/gnrc_rpl_dodag.c b/sys/net/gnrc/routing/rpl/gnrc_rpl_dodag.c
index e75c93fee2b627aff3d38e6eb4d8970840bba436..6dae5b5c462a7798d94303f2796d3963a2bac95a 100644
--- a/sys/net/gnrc/routing/rpl/gnrc_rpl_dodag.c
+++ b/sys/net/gnrc/routing/rpl/gnrc_rpl_dodag.c
@@ -32,7 +32,11 @@
 static char addr_str[IPV6_ADDR_MAX_STR_LEN];
 #endif
 
-void rpl_trickle_send_dio(void *args)
+static gnrc_rpl_parent_t *_gnrc_rpl_find_preferred_parent(gnrc_rpl_dodag_t *dodag);
+static void _rpl_trickle_send_dio(void *args);
+static int _compare_parents(gnrc_rpl_parent_t *p1, gnrc_rpl_parent_t *p2);
+
+static void _rpl_trickle_send_dio(void *args)
 {
     gnrc_rpl_dodag_t *dodag = (gnrc_rpl_dodag_t *) args;
     ipv6_addr_t all_RPL_nodes = GNRC_RPL_ALL_NODES_ADDR;
@@ -144,7 +148,7 @@ bool gnrc_rpl_dodag_add(gnrc_rpl_instance_t *instance, ipv6_addr_t *dodag_id, gn
         (*dodag)->addr_preferred = GNRC_RPL_DEFAULT_PREFIX_LIFETIME;
         (*dodag)->addr_valid = GNRC_RPL_DEFAULT_PREFIX_LIFETIME;
         (*dodag)->my_rank = GNRC_RPL_INFINITE_RANK;
-        (*dodag)->trickle.callback.func = &rpl_trickle_send_dio;
+        (*dodag)->trickle.callback.func = &_rpl_trickle_send_dio;
         (*dodag)->trickle.callback.args = *dodag;
         (*dodag)->dio_interval_doubl = GNRC_RPL_DEFAULT_DIO_INTERVAL_DOUBLINGS;
         (*dodag)->dio_min = GNRC_RPL_DEFAULT_DIO_INTERVAL_MIN;
@@ -352,7 +356,7 @@ void gnrc_rpl_parent_update(gnrc_rpl_dodag_t *dodag, gnrc_rpl_parent_t *parent)
         }
     }
 
-    if (gnrc_rpl_find_preferred_parent(dodag) == NULL) {
+    if (_gnrc_rpl_find_preferred_parent(dodag) == NULL) {
         gnrc_rpl_local_repair(dodag);
     }
 
@@ -361,23 +365,27 @@ void gnrc_rpl_parent_update(gnrc_rpl_dodag_t *dodag, gnrc_rpl_parent_t *parent)
     }
 }
 
-int _compare_parents(gnrc_rpl_parent_t *p1, gnrc_rpl_parent_t *p2)
+static int _compare_parents(gnrc_rpl_parent_t *p1, gnrc_rpl_parent_t *p2)
 {
     return p1->dodag->instance->of->which_parent(p1, p2) == p1 ? -1 : 1;
 }
 
-gnrc_rpl_parent_t *gnrc_rpl_find_preferred_parent(gnrc_rpl_dodag_t *dodag)
+/**
+ * @brief   Find the parent with the lowest rank and update the DODAG's preferred parent
+ *
+ * @param[in] dodag     Pointer to the DODAG
+ *
+ * @return  Pointer to the preferred parent, on success.
+ * @return  NULL, otherwise.
+ */
+static gnrc_rpl_parent_t *_gnrc_rpl_find_preferred_parent(gnrc_rpl_dodag_t *dodag)
 {
     ipv6_addr_t def = IPV6_ADDR_UNSPECIFIED;
     gnrc_rpl_parent_t *old_best = dodag->parents;
 
     LL_SORT(dodag->parents, _compare_parents);
 
-    if (dodag->parents == NULL) {
-        return NULL;
-    }
-    else if (dodag->parents->rank >= dodag->my_rank) {
-        gnrc_rpl_parent_remove(dodag->parents);
+    if ((dodag->parents == NULL) || (dodag->parents->rank >= dodag->my_rank)) {
         return NULL;
     }
 
diff --git a/sys/net/gnrc/routing/rpl/of0.c b/sys/net/gnrc/routing/rpl/of0.c
index df1ee0a1dcbe0264f61605281b7212b6adb860f7..3bd5d5faee08e2c9ce5570d3073c99a592471e3c 100644
--- a/sys/net/gnrc/routing/rpl/of0.c
+++ b/sys/net/gnrc/routing/rpl/of0.c
@@ -86,7 +86,7 @@ gnrc_rpl_parent_t *which_parent(gnrc_rpl_parent_t *p1, gnrc_rpl_parent_t *p2)
     return p2;
 }
 
-/* Not used yet, as the implementation only makes use of one dodag for now. */
+/* Not used yet */
 gnrc_rpl_dodag_t *which_dodag(gnrc_rpl_dodag_t *d1, gnrc_rpl_dodag_t *d2)
 {
     (void) d2;