Threads appears to have a retention problem, with less than half of the users that originally signed up continuing to use the platform.

Threads is Meta’s Twitter-killer, and launched to quite a bit of fanfare. The platform crossed 100 million users within the first five days, but it appears most of those users are not sticking around

“If you have more than 100 million people sign up, ideally it would be awesome if all of them or even half of them stuck around. We’re not there yet,” Meta CEO Mark Zuckerberg said, according to BBC.

The app recently got “Following” and “For You” features, which may go a long way toward keeping people engaged.

Ultimately, Meta will need to address its Threads retention issue if it plans to make measurable headway against Twitter.