PITTSBURGH (KDKA) – If you have an older iPhone or iPad, you’ll want to update to the latest iOS before Sunday.

Otherwise, you won’t be able to connect to use certain functions.

It has to do with a GPS clock reset that happened back in April.

The update affects iPhone 5-S and 4-S models, as well as iPad 2-S, iPad retina display and the fourth generation iPad.

If you don’t update your iPad or iPhone by Sunday, you’ll have to connect it to a computer and do the update manually.

To find out if your device is up to date, visit Apple’s website.