On Tuesday, Open Whisper Systems revealed in a blog post that has completed work to integrate its encryption technology into the Facebook-owned (FB) app. Now, all WhatsApp chats, group chats, attachments, voice notes, and voice calls on Android, iPhone, Windows Phone, Nokia S40, Nokia S60, Blackberry, and BB10 devices will be protected with strong encryption if the user is running the latest version of the app. Moreover, the app will make it clear whether a message is encrypted or not, which can be useful if, say, one user in a group chat isn’t running the latest version. The group will be notified of which messages are encrypted and which aren’t.

A WhatsApp spokesman confirmed the two companies’ collaboration on the effort.

In February, WhatsApp co-founder and CEO Jan Koum publicly came out in support of Apple’s (AAPL) stance against the FBI’s push that it help it unlock an iPhone belonging to one of the San Bernardino shooters.

“I have always admired Tim Cook for his stance on privacy and Apple’s efforts to protect user data and couldn’t agree more with everything said in their Customer Letter today,” he wrote in a Facebook post at the time. “We must not allow this dangerous precedent to be set. Today our freedom and our liberty is at stake.”

In 2014, WhatsApp introduced strong encryption of messages using the TextSecure protocol, though it could switch it off without notifying users, according to The Verge.

Encrypted messaging apps like Open Whisper Systems’ own app, Signal, and Telegram have grown in popularity among consumers concerned about privacy as well as encryption experts.