Apple last week released its latest mobile operating system, which has some great new features like Apple News, better battery life, and split-screen multitasking. But one new feature, called Wi-Fi Assist, may be eating through your data plan.

The new setting, which is automatically turned on when a phone is updated to iOS 9, attempts to ensure that users don’t experience any buffering when on a weak WiFi signal. The iPhone will detect when a WiFi signal lacks strength, and switch over to a cellular connection.

This is great for when you’re stuck in places like the connectivity nexus right outside your home, where old iPhones would cling to the WiFi signal for as long as possible, but wouldn’t actually be able to load anything. But there is a cost: The switch to cellular could mean you’re using more data from your monthly plan—potentially significantly more than you’re accustomed to using.

If you’re on a wireless plan with a fixed amount of data each month, it might be worth checking to see if your data consumption has risen. (I checked my data on my iPhone 6—I tend to use about 1 GB a month, and I’ve apparently used close to 3 GB this month.) Head to Settings > Cellular to see your data tally, and scroll to the bottom to see if Wi-Fi Assist is on.

Down at the bottom of Settings > Cellular

The increased data consumption is not a bug, and Apple appears to be aware of the issue. Switching the setting to the off mode should bring your consumption back in line with your normal usage.