diff --git a/sys/xtimer/xtimer.c b/sys/xtimer/xtimer.c
index 8918ae86f7c34b61453c193041384d58188de95b..97549435bbd2b384371157dbe0fee626982bf311 100644
--- a/sys/xtimer/xtimer.c
+++ b/sys/xtimer/xtimer.c
@@ -39,6 +39,7 @@ void _xtimer_sleep(uint32_t offset, uint32_t long_offset)
     if (irq_is_in()) {
         assert(!long_offset);
         xtimer_spin(offset);
+        return;
     }
 
     xtimer_t timer;