diff --git a/platform/wismote/contiki-wismote-main.c b/platform/wismote/contiki-wismote-main.c
index f2da75a6c..8a79811ac 100644
--- a/platform/wismote/contiki-wismote-main.c
+++ b/platform/wismote/contiki-wismote-main.c
@@ -257,7 +257,7 @@ main(int argc, char **argv)
   init_platform();
 
   set_rime_addr();
-  random_init(linkaddr_node_addr.u8[6] + linkaddr_node_addr.u8[7]);
+  random_init(linkaddr_node_addr.u8[LINKADDR_SIZE-2] + linkaddr_node_addr.u8[LINKADDR_SIZE-1]);
 
   cc2520_init();
   {