WhatsApp users could soon get a new "secret code" function that makes sure nobody ever sees their most private messages.

The update, which has been spotted by the eagle-eyed team at WABetainfo, appears to fix a strange glitch with the recently released Chat Lock option.

For those not aware, Chat Lock makes sure conversations are tucked behind an additional layer of security and can't be read until biometrics such as Face ID or fingerprints are confirmed. To set this up you simply tap on a name at the top of the chat then scroll down and switch Chat Lock on.

It's a good way of keeping things secret but it only works on a primary device which means messages can still be read on other phones and laptops that happen to be linked to an account.

That's pretty scary for anyone who thought their conversations were protected without realising anyone with access to the second device can dig in and read what's being said.

Luckily this could change in the future with messages staying protected on all devices via this new secret code option.

As WABetinfo explains, "Entering a secret code will allow users to easily find locked chats even in the search bar of the app. In addition, configuring a secret code will allow users to lock chats even from companion devices."

Codes can be anything including letters, numbers and even emojis and need to be entered on devices to read any messages stored behind the Chat Lock protection.

Right now, this secret code option is only available via beta test but it could arrive soon on Android and iPhone.

Like all test versions of the app, there's no official news on a rollout but watch this space for more details.