When owning a smartphone, users understand they’re forgoing a certain level of privacy. Apps can access contacts, email, and even location. Now, a report from The New York Times reveals the privacy rabbit hole goes even deeper than we imagined.

The report claims over 250 games in the Google Play Store have been using smartphone microphones to eavesdrop on users—but not for the reason you’d think. Apparently, these games are interested in learning the TV habits of users, resulting in tailored ads.

The New York Times explains:

The apps use software from Alphonso, a start-up that collects TV-viewing data for advertisers. Using a smartphone’s microphone, Alphonso’s software can detail what people watch by identifying audio signals in TV ads and shows, sometimes even matching that information with the places people visit and the movies they see.

Worryingly, some apps are capable of detecting sounds when a user has their phone in their pocket, even when the app isn’t open.

According to Alphonso chief executive Ashish Chordia, the consumer has to give permission to these games in order for them to access the microphone, so there’s never any surreptitious monitoring going on. If you have mistakenly given permission to this level of monitoring, Alphonso provides opt-out instructions on its website.

To limit an app’s access to your microphone, go to your phone’s Settings > Apps > Select the app > Permissions > Turn off access.

If you’re playing a game like Trash Toss, there’s no reason to give that app access to your microphone. To hear that some incredibly popular games are eavesdropping on your TV habits should be reason enough to stop microphone access for good.

In addition to these games appearing on the Google Play Store, the same report claims some have also appeared in the iOS App Store.