If you’ve downloaded the macOS version of HandBreak, a popular video transcoding program that converts multimedia files into different formats, checking your computer’s safety right now would be wise. Users who downloaded the program between May 2 and May 6 have a 50 percent chance of being infected with an Apple Trojan, based on an announcement on HandBrake’s website.

MacOS has a reputation for being one of the most secure operating systems. But in 2016, its susceptibility to malware grew by an astounding 744% according to one security report. Recently, a new strain of malware was found to infiltrate Macs by bypassing all of its security features.