Apple has rolled out a firmware update for the mid-2015 MacBook Pro family that promises to address a serious flash storage problem that could result in data corruption. It weighs in at just 1.9MB, and you’ll want to download and install it as soon as you can.

“This update is recommended for MacBook Pro (mid 2015) models,” Apple’s release notes read. “This update addresses a storage firmware issue that, in rare cases, may cause data corruption.”

Apple doesn’t provide any more details on the issue, but it’s somewhat worrying that it had the potential to destroy users’ data and this is the first time the vast majority will find out about it. This is why it’s important to backup your machines on a regular basis if you value the things you have stored on them.

You should also make sure you download and install this firmware update as soon as you possibly can to get the fix. It’s only small, so it won’t take long to download — but it will require you to restart your machine. You can download the update now via the Mac App Store, or from Apple’s support page linked below.