Microsoft will add a new feature to Windows Defender that will help block ransomware from being able to encrypt certain files.

Yesterday, Microsoft announced that it will be adding the feature as a way to combat ransomware. The addition to Windows Defender will come with the feature turned off and must be enabled for it to work. This feature will compare a list of known apps (called a whitelist) to any app attempting to make changes to specially designated files.

Ransomware, once installed on a computer, encrypts files and locks users out of their own data until a ransom is paid. This new feature will help stop it from being able to encrypt those files.

“Controlled folder access monitors the changes that apps make to files in certain protected folders,” said Dona Sarkar, of Microsoft’s Windows Insiders program. “If an app attempts to make a change to these files, and the app is blacklisted by the feature, you’ll get a notification about the attempt.”