As well as addressing a serious security flaw, Apple's latest update also brings a number of new features and is available to download now.
The update addresses a critical security hole, christened the "goto fail," a potentially devastating flaw that left Mac users' information exposed when on shared networks or accessing wi-fi hotspots.
An attacker could intercept sensitive data such as email log-ins or trick a computer into thinking that a fake sign-in page was the real thing and dupe people into revealing user names and passwords.
On Friday, Apple pushed out a fix for the flaw for iPhone, iPad and iPod Touch users and it has now also pushed out a fix for its computers.If you're using a Mac that runs Mavericks and you use wi-fi or a shared network, the company's advice is to install the update as soon as possible.
As well as closing the hole, the update also brings the ability to make voice-only FaceTime calls to the desktop and the ability to block iMessages from specific users. It also addresses one or two bugs in Apple's mail client.