diff --git a/sys/net/sixlowpan/rpl/trickle.c b/sys/net/sixlowpan/rpl/trickle.c
index eca3eb66fc..e1201ad3f9 100644
--- a/sys/net/sixlowpan/rpl/trickle.c
+++ b/sys/net/sixlowpan/rpl/trickle.c
@@ -111,7 +111,7 @@ void trickle_interval_over(void){
 	while(1){
 		thread_sleep();
 		I = I*2;
-		printf("TRICKLE new Interval %lu\n",I);
+		printf("TRICKLE new Interval %u\n",I);
 		if( I == 0 ){
 			puts("[WARNING] Interval was 0");
 			if( Imax == 0){
diff --git a/sys/net/sixlowpan/sixlowmac.c b/sys/net/sixlowpan/sixlowmac.c
index e000f08695..0d772fea86 100644
--- a/sys/net/sixlowpan/sixlowmac.c
+++ b/sys/net/sixlowpan/sixlowmac.c
@@ -191,7 +191,7 @@ void send_ieee802154_frame(ieee_802154_long_t *addr, uint8_t *payload,
 
     p.data = buf;
     msg_send_receive(&mesg, &transceiver_rsp, transceiver_pid);
-    printf("%s, %u: %lu\n", __FILE__, __LINE__, transceiver_rsp.content.value);
+    printf("%s, %u: %u\n", __FILE__, __LINE__, transceiver_rsp.content.value);
 
     hwtimer_wait(5000);
 }