diff --git a/core/net/rpl/rpl.c b/core/net/rpl/rpl.c
index 9fca4c28e..c1384b0b6 100644
--- a/core/net/rpl/rpl.c
+++ b/core/net/rpl/rpl.c
@@ -308,6 +308,8 @@ rpl_init(void)
 #if RPL_CONF_STATS
   memset(&rpl_stats, 0, sizeof(rpl_stats));
 #endif
+
+  RPL_OF.reset(NULL);
 }
 /*---------------------------------------------------------------------------*/
 #endif /* UIP_CONF_IPV6 */
diff --git a/core/net/rpl/rpl.h b/core/net/rpl/rpl.h
index 562961d84..76134e44e 100644
--- a/core/net/rpl/rpl.h
+++ b/core/net/rpl/rpl.h
@@ -189,6 +189,9 @@ struct rpl_of {
   rpl_ocp_t ocp;
 };
 typedef struct rpl_of rpl_of_t;
+
+/* Declare the selected objective function. */
+extern rpl_of_t RPL_OF;
 /*---------------------------------------------------------------------------*/
 /* Instance */
 struct rpl_instance {