10/01/2015 11:52 EDT | Updated 10/02/2015 10:59 EDT

This iOS 9 Feature Might Secretly Rack Up Your Phone Bill

A new feature in the iOS 9 software update might eat up your data and send your bill skyrocketing.

The feature, called "WiFi assist," is already turned on by default, and what it does is switch you to 4G if it thinks your WiFi signal isn't strong enough. For those without a good data plan, this could mean hundreds of extra dollars spent on cell phone bills.

Thankfully, turning off the feature is fairly painless.

1. Access your phone's settings page.

2. Open the "cellular" menu.

3. Scroll far down to "WiFi Assist," and slide the button over to turn off the feature.

4. You're welcome.

With more than half of iPhone users already updated, this is the fastest iOS transition to date, according to Apple. Watch the video above for the full story.

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