Apple’s latest iOS 9.1 update came out last week, and it brings plenty of new features, including Emoji. If you haven’t updated yet, you should do so while you’re awake — or risk sleeping in.

According to readers speaking with AppleInsider, there’s a bug inside the iOS 9.1 update that’s causing folks who have decided to apply the update automatically overnight to sleep through their alarms. Actually, it’s worse than that: the alarms aren’t going off at all, it seems. This issue has apparently been floating around since Apple introduced the overnight update feature in iOS 9.

So beware before you set you decide to update using the overnight function, sleepyheads. Install the updates while you’re awake, unless you want to risk missing the bus to work tomorrow.