diff --git a/core/net/mac/xmac.c b/core/net/mac/xmac.c
index 02050575c..32d6697a2 100644
--- a/core/net/mac/xmac.c
+++ b/core/net/mac/xmac.c
@@ -30,7 +30,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: xmac.c,v 1.4 2007/05/22 20:55:24 adamdunkels Exp $
+ * $Id: xmac.c,v 1.5 2007/05/22 22:10:30 oliverschmidt Exp $
  */
 
 /**
@@ -184,7 +184,8 @@ powercycle(struct rtimer *t, void *ptr)
       radio->off();
       radio_is_on = 0;
       LEDS_OFF(LEDS_RED);
-      if(rtimer_set(t, RTIMER_TIME(t) + OFF_TIME, 1, powercycle, ptr)) {
+      if(rtimer_set(t, RTIMER_TIME(t) + OFF_TIME, 1,
+		    (void (*)(struct rtimer *, void *))powercycle, ptr)) {
 	PRINTF("xmac: could not set long off rtimer\n");
       }
       long_off = 0;