Oof. Karen Blaha/Flickr (CC) Macs have long enjoyed a reputation as being virus-free compared to the constant security scares affecting Windows machines.

But the reality isn't that simple.

The number of cases of affecting Macs has surged wildly over the last year — growing by a huge 744% in 2016, according to the new McAfee Threat Report.

(We first saw it over on 9to5Mac, and you can read the full report below.)

The security firm detected 460,000 instances of malware on Macs. (That means it found nearly half a million infections — not half a million different types of malware.)

The reason for this huge growth is adware bundling, McAfee says.

In other words, people are installing apps that come bundled with dodgy software ("adware") that sticks ads on their computer. It's invasive, but it's not necessarily as catastrophic as other types of malware — like ransomware, which encrypts your data and forces you to pay a ransom to get it back (though multiple kinds can come bundled together, of course). Wowza. McAfee

Apple offers an App Store on desktop, much like it does on iOS. By only using apps from there or trusted sources, users can mitigate their chances of getting hit. Use common sense, don't install apps from shady sources or unknown developers, and be careful what else it asks to install during the install process.

And remember: The 744% growth sounds alarming — but it's still nothing compared to the amount of malware for Windows that McAfee identified.

Nearly 640 million malware instances were found overall by McAfee — with the vast majority of these coming from Windows. The Mac malware is still a drop in the ocean in comparison.

Here's the full report from McAfee: