Buried inside Twitter’s  Android app is a “Secret conversation” option that if launched would allow users to send encrypted direct messages. The feature could make Twitter a better home for sensitive communications that often end up on encrypted messaging apps like Signal, Telegram or WhatsApp.

The encrypted DMs option was first spotted inside the Twitter for Android application package (APK) by Jane Manchun Wong. APKs often contain code for unlaunched features that companies are quietly testing or will soon make available. A Twitter spokesperson declined to comment on the record. It’s unclear how long it might be before Twitter officially launches the feature, but at least we know it’s been built.

The appearance of encrypted DMs comes 18 months after whistleblower Edward Snowden asked Twitter CEO Jack Dorsey for the feature, which Dorsey said was “reasonable and something we’ll think about.”

Twitter has gone from “thinking about” the feature to prototyping it. The screenshot above shows the options to learn more about encrypted messaging, start a secret conversation and view both your own and your conversation partner’s encryption keys to verify a secure connection.

Twitter’s DMs have become a powerful way for people to contact strangers without needing their phone number or email address. Whether it’s to send a reporter a scoop, warn someone of a problem, discuss business or just “slide into their DMs” to flirt, Twitter has established one of the most open messaging mediums. But without encryption, those messages are subject to snooping by governments, hackers or Twitter itself.

Twitter has long positioned itself as a facilitator of political discourse and even uprisings. But anyone seriously worried about the consequences of political dissonance, whistleblowing or leaking should be using an app like Signal that offers strong end-to-end encryption. Launching encrypted DMs could win back some of those change-makers and protect those still on Twitter.