Apple put out a security and stability update for OS X El Capitan on Tuesday. There are no new features, but quite a few stability and security tweaks.

The update, 10.11.3, is recommended for all users. It “fixes an issue that may prevent some Mac computers from waking from sleep when connected to certain 4K displays,” according to Apple, and also “improves the stability, compatibility, and security of your Mac”.

It’s a maddeningly unspecific set of release notes, sure, but those who are interested can dive into Apple’s security notes about the update to see the many tweaks included. Quite a few element of the operating system were patched to prevent “arbitrary code with kernel privileges” from running, which is without question a good thing.

The update also comes with a patch for Safari, 9.0.3, which prevents malicious websites from arbitrarily running code. An update for Webkit, the engine that powers Safari, helps protect a potential privacy problem that could let websites “know if the user has visited a given link”.

If you’re yet to update to El Capitan, this update still means something for you: “Third-party .pkg file receipts stored in /var/db/receipts are now retained when upgrading from OS X Yosemite”, the release notes say. El Capitan clears out a lot of third-party tweaks when you upgrade, as part of their new “rootless” security structure. In some cases, El Capitan left no trace of such apps. This has presumably been a nightmare for IT folks, who at least now will have some record of their now-missing apps.

The updates is a 661 megabyte download, and installation requires a restart. The process took around 20 minutes for this reporter. As always, it’s a good idea to backup all of your data before upgrading your operating system.