diff --git a/sys/platform/vkernel64/platform/systimer.c b/sys/platform/vkernel64/platform/systimer.c
index f84a5b1..fe0c829 100644
--- a/sys/platform/vkernel64/platform/systimer.c
+++ b/sys/platform/vkernel64/platform/systimer.c
@@ -299,7 +299,7 @@ vktimer_intr_reload(struct cputimer_intr *cti __unused, sysclock_t reload)
 	reload += sys_cputimer->count();
 	vktimer_reload[mycpu->gd_cpuid] = reload;
 	if (vktimer_cotd && (ssysclock_t)(reload - vktimer_target) < 0) {
-		while ((sysclock_t)(reload - vktimer_target) < 0)
+		while ((ssysclock_t)(reload - vktimer_target) < 0)
 			reload = atomic_swap_long(&vktimer_target, reload);
 		cothread_wakeup(vktimer_cotd, &vktimer_ts);
 	}