David Letterman is less than a month away from his final Late Show. He’s in farewell-tour mode, and he’s only booking his favorites to appear on his show. Last night, Elvis Costello made his 27th and presumably last Letterman appearance, and he went out on a great note. Backed only by the doo-wop-style vocal trio the Quills and his own acoustic guitar, Costello covered his friend Nick Lowe’s 1980 song “When I Write The Book,” working in a bit of his own 1983 single “Everyday I Write The Book” as well. It’s a lovely performance, and you can watch it below.

I guess we’ll figure out who Letterman really likes over the next few weeks, won’t we?