It isn’t uncommon for me to have three nearly identical power cables plugged in to my surge protector—my iMac, MacBook Air, and iPad all have the light gray, standard-issue Apple three-prong power plugs, and I’ve unplugged the wrong thing on more than one occasion. To prevent this from happening again, I recently enlisted the help of a permanent marker.

Grab your favorite permanent marker—in my case, a Sharpie fine-point marker—and write a description of that power cable on the power plug’s rubber housing. In my case, I wrote “iMac” for my iMac, “iPad” for my iPad, and “MBA” for my MacBook Air.

If you’re feeling more creative, you could draw a small symbol for each device, or even color-code them. Find an approach that works for you, and never again unplug your iMac when you meant to unplug your MacBook.