Do you have a first edition copy of Harry Potter and the Philosopher's Stone? We're talking books here.
Well, if you do, it might be worth (up to, obviously) £20,000 at auction.
This is all because of a printing error on page 53 of the book, which you should be running to check right now.
Here's the error in question. Blink and you'll miss it.
Did you spot it?
If you didn't, look at that list again, and note that "1 wand" has been written in twice.
Apparently, there's 500 hardback copies of this book which feature this error, and of course, after that they were all corrected.
"As the first book in the series, Harry Potter and the Philosopher's Stone has a special place in the affections of the millions of readers across the world and the proof reading error about the wand in the first edition has, of course, become a treasured piece of Harry Potter arcana," said Matthew Haley, who is the head of Bonhams Books and Manuscripts.
Of course, your book will have to be in mint condition for it to fetch the top price. That's how collecting works.
If you have one of these books, in any condition (it still might be worth a few quid), then get in touch with Bonhams.
Call them on 020 7447 7447, or email them at [email protected] All the other contacts you could ever need are in the link above.