Apple’s new mobile operating system iOS 9 was affected by several bugs since its release earlier this month. But if your cellular data usage has jumped significantly since upgrading to iOS 9, it is most likely a new feature rather than a bug. Alongside Apple News, an improved Maps, and enhanced battery life, the new mobile OS also brings a feature called WiFi Assist.

How To Prevent iOS 9 'WiFi Assist' From Sucking All Your Data

Users report significant jump in data consumption

WiFi Assist is automatically turned on when you update your iPhone to the iOS 9. It detects when the WiFi connectivity lacks strength, and switches automatically to a cellular connection. It ensures that you don’t experience any buffering even when on a poor WiFi signal. That would be great if you are on an unlimited data plan. But it may significantly increase your bill if you are on a fixed monthly data plan.

Many users have reported an increase in the use of their cellular data. Jim Ray, an iPhone user, reported that his mobile data use skyrocketed to 7GB this month from the usual 1-2GB a month. You have to turn off the WiFi Assist to avoid being surprised by an expensive cellphone bill. Of course, it will deprive your phone the ability to switch between cellular and WiFi automatically. Mike Murphy of Quartz first spotted the issue.

Apple aware of the iOS 9 WiFi Assist issue

Go to Settings > Cellular (Mobile Data in certain regions), and scroll to the bottom. There you can turn off WiFi Assist. It should bring your data consumption back to the normal usage. According to Quartz, Apple is fully aware of the issue. You can keep an eye on data usage by using the Reset Statistics feature that is located right below the WiFi Assist toggle.

Apple’s iOS 9 was also affected by crashing issues, battery problems, and a bug that affected apps running on iPhone 6S that use the gyroscope and compass data.