In the New Year, older iPhone or Android models may lose access to the instant messaging app's features - or the service altogether - as support will stop for users without at least iOS 9 or Android 4.0.3 on their device.
As reported by Tech Radar, people with an iPhone 4 or below won't be able to upgrade to the latest software, while much older Android handsets - including 2011's Samsung Galaxy S2 - won't be able to upgrade.
For anyone concerned they might lose access, it's worth checking as some WhatsApp users will be able to upgrade their software to higher than Android 4.0.3 or iOS 9.
For iPhone users, you can make sure by heading to Settings, General, and then Software update to see what you're running.
For Android customers, you simply go to Settings and About Phone.
However, some users with much older devices won't be able to upgrade their software, which means they'll lose access to certain WhatsApp features from January 1 - or even access to the app altogether.