Justin Vernon wasn’t officially scheduled to perform at Glastonbury, but he made a surprise appearance at Kanye’s climactic headlining set yesterday. And while he was there, he also found the time to join his old friends the Staves. Vernon recorded and produced the UK sister trio’s lovely LP If I Was at his mythical Wisconsin studio — they described him as their “Gandalf” — and he contributed vocals and guitar to highlight “Make It Holy.” He’s made a habit of coming out to perform the song live with them at shows, and he did it again today, showcasing their immense musical chemistry and some killer harmonies in a stunning performance on the Park Stage. Watch it below.