Mac DeMarco already sold one pair of dirty old shoes for over $20,000 and donated the proceeds to charity. And it apparently worked out so well that he’s decided to sell more dirty old shoes for charity. Pitchfork reports that DeMarco, Paul McCartney, Lorde, Grimes, Killer Mike, and more are all auctioning off used and signed footwear through Charity Stars to benefit the Small Steps Project, a UK-based nonprofit that provides aid to children who live on landfills and garbage dumps. Check out some of the shoes below and find the full auction here.

Get @Msldemarco @VANS_66 doodled on at @wayoutwestgbg at #CelebrityShoeAuction https://t.co/WYEbhg0uIS why? see here https://t.co/5ZlRan3G84 pic.twitter.com/Ysi2nPPehD

— Small Steps Project (@SmallStepsDocs) November 4, 2017

#runthejewels @KillerMike @GlastoFest @nikebasketball LIVE #CelebrityShoeAuction https://t.co/pRjaoihbcZ help kids pic.twitter.com/hiBzZfUGf6

— Small Steps Project (@SmallStepsDocs) November 5, 2017

Signed @Grimezsz boots live for bids in #CelebrityShoeAuction to help children off landfills https://t.co/rzKAh5oLNC https://t.co/5ZlRan3G84 pic.twitter.com/vOVfBqe86k

— Small Steps Project (@SmallStepsDocs) November 2, 2017

The auction 4 the SIGNED superstars that Lorde donated to the @smallstepsdocs charity is now underway! U can bid @ https://t.co/M7bu09GBwu pic.twitter.com/xZkTyjUXeo

— Lorde_fix (@Lorde_fix) November 1, 2017