diff --git a/core/net/mac/contikimac/contikimac.c b/core/net/mac/contikimac/contikimac.c
index b8fc35c02..186ce743b 100644
--- a/core/net/mac/contikimac/contikimac.c
+++ b/core/net/mac/contikimac/contikimac.c
@@ -290,6 +290,7 @@ off(void)
 }
 /*---------------------------------------------------------------------------*/
 static volatile rtimer_clock_t cycle_start;
+static void powercycle_wrapper(struct rtimer *t, void *ptr);
 static char powercycle(struct rtimer *t, void *ptr);
 static void
 schedule_powercycle(struct rtimer *t, rtimer_clock_t time)
@@ -302,8 +303,7 @@ schedule_powercycle(struct rtimer *t, rtimer_clock_t time)
       time = RTIMER_NOW() - RTIMER_TIME(t) + 2;
     }
 
-    r = rtimer_set(t, RTIMER_TIME(t) + time, 1,
-                   (void (*)(struct rtimer *, void *))powercycle, NULL);
+    r = rtimer_set(t, RTIMER_TIME(t) + time, 1, powercycle_wrapper, NULL);
     if(r != RTIMER_OK) {
       PRINTF("schedule_powercycle: could not set rtimer\n");
     }
@@ -321,8 +321,7 @@ schedule_powercycle_fixed(struct rtimer *t, rtimer_clock_t fixed_time)
       fixed_time = RTIMER_NOW() + 1;
     }
 
-    r = rtimer_set(t, fixed_time, 1,
-                   (void (*)(struct rtimer *, void *))powercycle, NULL);
+    r = rtimer_set(t, fixed_time, 1, powercycle_wrapper, NULL);
     if(r != RTIMER_OK) {
       PRINTF("schedule_powercycle: could not set rtimer\n");
     }
@@ -354,6 +353,12 @@ powercycle_turn_radio_on(void)
   }
 }
 /*---------------------------------------------------------------------------*/
+static void
+powercycle_wrapper(struct rtimer *t, void *ptr)
+{
+  powercycle(t, ptr);
+}
+/*---------------------------------------------------------------------------*/
 static char
 powercycle(struct rtimer *t, void *ptr)
 {
@@ -1015,8 +1020,7 @@ init(void)
   radio_is_on = 0;
   PT_INIT(&pt);
 
-  rtimer_set(&rt, RTIMER_NOW() + CYCLE_TIME, 1,
-             (void (*)(struct rtimer *, void *))powercycle, NULL);
+  rtimer_set(&rt, RTIMER_NOW() + CYCLE_TIME, 1, powercycle_wrapper, NULL);
 
   contikimac_is_on = 1;
 
@@ -1032,8 +1036,7 @@ turn_on(void)
   if(contikimac_is_on == 0) {
     contikimac_is_on = 1;
     contikimac_keep_radio_on = 0;
-    rtimer_set(&rt, RTIMER_NOW() + CYCLE_TIME, 1,
-               (void (*)(struct rtimer *, void *))powercycle, NULL);
+    rtimer_set(&rt, RTIMER_NOW() + CYCLE_TIME, 1, powercycle_wrapper, NULL);
   }
   return 1;
 }