I looked it up in the Random House Unabridged after I posted, and it says Zen's right and I'm wrong. Also, I looked up malaprop in The King's English and the Fowler brothers used it, so it's approved for British speakers.

The problem with the Oxford is that they do these massive main editions periodically, and then they issue smaller dictionaries that contain the words they missed in the big edition. So you have to check the big Oxford plus any relevant small Oxfords.

I just reread that last sentence and it sounds like I'm talking about shoes.