Mark a folder as 'Permanent' in VS Setup Project

When creating a Setup Project in Visual Studio you can specify that a file is Permanent, but there is no option for setting a folder as such. My installer needs to copy some files to an existing (sometimes empty) folder, but when it uninstalls it deletes the folder if it's empty. I'd like to prevent that so it doesn't break other add-ins. Right now I've added a dummy.txt file 开发者_如何学编程and set it as permanent so the folder isn't deleted. Is there another way?