The humble font isn’t as humble as you might think, especially on a Mac. Fonts are more like plug-ins than you’d imagine, and because they’re loaded by macOS and the apps that run on it, a bad font can have some unexpected consequences.

Those consequences can range from the relatively benign, like some characters being displayed incorrectly, to something more annoying, like apps refusing to load or functions not working quite as they used to. Faulty fonts are rarely the cause of macOS system problems, but if you’re experiencing issues that don’t make a great deal of sense, checking out your fonts is a great first troubleshooting step to take.

Thankfully, Apple includes a tool for installing, validating and generally troubleshooting fonts with each Mac. The next time your Mac is misbehaving, and you’re out of ideas, validating your fonts is a good troubleshooting step.