Facebook is planning an app that tracks the location of users, according to a report from Bloomberg. The feature would be able to run on a handset even when the app isn’t open, and it may be used to help the company target ads based on location.

Both Google and Apple have created location-logging and -broadcasting apps (Latitude and Find My Friends, respectively). While they’re fine for use with close friends, it hasn’t exactly become de rigueur to casually broadcast one’s location to vast swaths of people at once. Facebook check-ins are one thing; a real-time homing beacon is something else.

According to Bloomberg, Facebook may use not only locations, but also “daily habits” of users’ travels on this great green earth to feed them targeted ads (or more likely, the somewhat less invasive promoted and sponsored posts).

It’s not hard to imagine Facebook is already doing this based on check-ins. But if the feature can provide a constant feed of visited locations, or even better, locations where the user is passing by without patronizing, the advertising opportunities may prove tempting for local businesses or chains that want to poach from each other.

An app that passively logs locations and sends them to Facebook’s servers makes us nervous. We can only hope that an on/off switch in Facebook’s privacy controls accompanies any eventual rollout.