WhatsApp is to cease support for a number of operating systems by the end of 2016, the company announced yesterday.

With Android and iOS dominating the smartphone realm, and Microsoft’s Windows Phone / Windows 10 Mobile still clinging on, the Facebook-owned company has revealed it will end support for BlackBerry (including BlackBerry 10), Nokia S40, and Nokia Symbian S60 by the end of this year. Additionally, it will no longer support Android 2.1 and 2.2 or Windows Phone 7.1.

The news comes in the same week that WhatsApp celebrated its seventh anniversary and also comes shortly after it passed one billion monthly active users (MAUs).

“When we started WhatsApp in 2009, people’s use of mobile devices looked very different from today,” the announcement read. “The Apple App Store was only a few months old. About 70 percent of smartphones sold at the time had operating systems offered by BlackBerry and Nokia. Mobile operating systems offered by Google, Apple and Microsoft – which account for 99.5 percent of sales today – were on less than 25 percent of mobile devices sold at the time. As we look ahead to our next seven years, we want to focus our efforts on the mobile platforms the vast majority of people use.”

While the news will no doubt be greeted with dismay in many regions, particularly developing markets where Nokia’s older operating systems still enjoy some market share, it makes sense for a company to focus its efforts on platforms that the vast majority of its users are on. WhatsApp has evolved a great deal since its inception as a simple mobile-messaging app — it now offers voice calls, and video calls are reportedly being added too. And it seems this, in part at least, explains why the company is looking to refocus its efforts in terms of the platforms it supports.

“While these mobile devices have been an important part of our story, they don’t offer the kind of capabilities we need to expand our app’s features in the future,” the announcement explained. “This was a tough decision for us to make, but the right one in order to give people better ways to keep in touch with friends, family, and loved ones using WhatsApp.”

Moreover, when BlackBerry itself is no longer focusing on its native operating system, well, who can blame WhatsApp for ditching it?

Moving forward, WhatsApp has one piece of advice for any of its users who are still using one of the aforementioned operating systems: Upgrade to iPhone, a more modern Android, or a Windows Phone device by the end of 2016.