WhatsApp’s version of Snapchat Stories is already pulling in around 15 percent of the messaging app’s 1.2 billion users. Mark Zuckerberg today announced on Facebook’s Q1 earnings call that WhatsApp Status now has 175 million daily users after only launching in mid-February. That’s made more impressive because Status lives in a separate tab of WhatsApp, instead of showing up at the top of the home screen like Instagram Stories, Facebook Stories and Messenger Day.

This means WhatsApp’s Snapchat Stories clone is now bigger than Snapchat itself, joining Instagram Stories, which reached that distinction last month when it announced 200 million users.

WhatsApp Status lets users post photos and videos in a slideshow that their contacts can see, but that disappears in 24 hours. It replaced the old text-only “Status” product that functioned more like “away” messages, though WhatsApp eventually added the old feature back in the About section.

The news comes at an awkward time for WhatsApp, as today it suffered a service outage of more than an hour. “WhatsApp is aware of the issue and working to fix it as soon as possible,” a spokesperson told TechCrunch, and it expects service to be restored soon.

Critics questioned why Facebook needed to put a Stories product in each of its core apps, including its chat products Messenger and WhatsApp, rather than just Facebook and Instagram. But WhatsApp’s deep traction in international markets where Snapchat hasn’t caught on yet gave it an opportunity to be the first popular app to offer Stories in many countries. Not only has this given WhatsApp Status rapid growth, but it could box out Snapchat’s ability to grow in developing markets.