NEW YORK (AP) — Facebook users in the U.S. will soon be able to see which of their friends are in close proximity using a new feature the company is launching on Thursday.

Called “Nearby Friends,” the optional tool will only be available to people who choose to turn it on. The feature uses your smartphone’s GPS system to tell your Facebook friends you are nearby — provided they have the feature turned on. Rather than share your exact location, it will only show that you are nearby, say, within half a mile.