diff --git a/sys/xtimer/xtimer_core.c b/sys/xtimer/xtimer_core.c
index c52490e096..c299fac2d5 100644
--- a/sys/xtimer/xtimer_core.c
+++ b/sys/xtimer/xtimer_core.c
@@ -129,7 +129,7 @@ void _xtimer_set64(xtimer_t *timer, uint32_t offset, uint32_t long_offset)
 void _xtimer_set(xtimer_t *timer, uint32_t offset)
 {
     DEBUG("timer_set(): offset=%" PRIu32 " now=%" PRIu32 " (%" PRIu32 ")\n",
-          offset, xtimer_now(), _xtimer_lltimer_now().ticks32);
+          offset, xtimer_now().ticks32, _xtimer_lltimer_now());
     if (!timer->callback) {
         DEBUG("timer_set(): timer has no callback.\n");
         return;
@@ -436,8 +436,8 @@ static void _timer_callback(void)
     _in_handler = 1;
 
     DEBUG("_timer_callback() now=%" PRIu32 " (%" PRIu32 ")pleft=%" PRIu32 "\n",
-          xtimer_now().ticks32, _xtimer_lltimer_mask(xtimer_now()),
-          _xtimer_lltimer_mask(0xffffffff - xtimer_now()));
+          xtimer_now().ticks32, _xtimer_lltimer_mask(xtimer_now().ticks32),
+          _xtimer_lltimer_mask(0xffffffff - xtimer_now().ticks32));
 
     if (!timer_list_head) {
         DEBUG("_timer_callback(): tick\n");