Apple has rolled out a surprise update to its OS X El Capitan beta for registered developers. It is the platform’s fifth beta update so far, and it comes just one week after the release of beta 4.

Available to download now via the Mac App Store for those who already have El Capitan installed, or from Apple’s Developer Center, beta 5 is “recommended for all users,” the company says. It does not appear to contain any new features, but it does bring important bug fixes.

We can only assume that this update fixes a pretty significant bug, which is why Apple decided to release it just one week after beta 4 — but it’s not clear what the issue may have been, or how many users it affected. There’s no word on when the update will reach public beta users, either.

El Capitan will be a free update for all supported Macs when it makes its debut this fall. In addition to under-the-hood improvements, like the introduction of Metal, it brings a revamped Mission Control, Split View multitasking, Spotlight enhancements, and new features for Safari.

You can get a sneak peek at all that’s new in OS X El Capitan in our hands-on video.