diff --git a/platform/z1/contiki-z1-main.c b/platform/z1/contiki-z1-main.c
index 40731f5e3..e721c8cdf 100644
--- a/platform/z1/contiki-z1-main.c
+++ b/platform/z1/contiki-z1-main.c
@@ -105,6 +105,7 @@ static uint8_t is_gateway;
 #endif
 
 void init_platform(void);
+void clock_wait(int i);
 
 /*---------------------------------------------------------------------------*/
 #if 0