Facebook is testing a new feature for Messenger that allows users to better protect their messages from prying eyes. When enabled, users will need to authenticate their identity using Face ID, Touch ID, or their passcode before they can view their inbox, even if their phone is already unlocked. (The feature relies on your device’s security settings, so however you unlock your phone normally is how you’ll unlock the Messenger app.)

The company is currently testing the new security feature among a small percentage of Messenger’s iOS users, though it could eventually be available more widely, including on Android. “We want to give people more choices and controls to protect their private messages, and recently, we began testing a feature that lets you unlock the Messenger app using your device’s settings,” a Facebook spokesperson said in a statement. “It’s an added layer of privacy to prevent someone else from accessing your messages.”