The Disappearing Witch!

Can you solve this bewitching visual puzzle? Click or tap the image to turn the clock disc. Turn the clock to 13 o'clock and count 13 witches. Turn the clock to 12 midnight and count 12 witches. Which witch vanished? Where did she go?

It is more spellbinding if you have a real paper puzzle with a disc that you turn by hand. You can make it yourself by printing the Cutout Pattern (PDF) on paper or cardstock.