Did you know that the word for the irrational fear of Friday the 13th is paraskevidekatriaphobia? Neither did we, but what that supposedly unlucky day is good for—whenever it rolls around—is reminding us to test our backup systems. If something does go wrong, backups can save your bacon, but only if they’re actually working. So on Friday the 13th this month, take a few minutes to make sure you can restore files from Time Machine, see if you can boot from your bootable duplicate, and generally verify that your data really is being backed up successfully. And if you’ve already missed the 13th, today is a fine day to make up for it with a quick test.