Facebook may soon ask you to "upload a photo of yourself that clearly shows your face," to prove you're not a bot.

The company is using a new kind of captcha to verify whether a user is a real person. According to a screenshot of the identity test shared on Twitter on Tuesday and verified by Facebook, the prompt says: “Please upload a photo of yourself that clearly shows your face. We’ll check it and then permanently delete it from our servers.”

In a statement to WIRED, a Facebook spokesperson said the photo test is intended to “help us catch suspicious activity at various points of interaction on the site, including creating an account, sending Friend requests, setting up ads payments, and creating or editing ads.”

The process is automated, including identifying suspicious activity and checking the photo. To determine if the account is authentic, Facebook looks at whether the photo is unique. The Facebook spokesperson said the photo test is one of several methods, both automated and manual, used to detect suspicious activity.

The company declined to share details to prevent the system from being manipulated. Suspicious activity might include someone who consistently posts from New York and then starts posting from Russia.

Facial technology is increasingly common, such the use of Apple Face ID to authenticate users on iPhone X.

A since deleted screenshot from Twitter seemed to indicate that users are locked out of their accounts while the photo is being verified. A message said, “You Can’t Log In Right Now. We’ll get in touch with you after we’ve reviewed your photo. You’ll now be logged out of Facebook as a security precaution.” Facebook users who suspect their account has been compromised can go to Facebook.com/hacked.

The company would not say when it started using the technique, but in a post on Reddit users reported getting the same prompt in April.

The new authentication scheme is the second in recent weeks that relies on photos. Earlier this month, Facebook asked users to upload nude photos to Facebook Messenger, as part of an effort to prevent revenge porn. Facebook said it would use the nude photos to create a digital fingerprint against which to compare future posts. Facebook said the photos are hashed and then deleted from its servers.