Wilco have been down with Stephen Colbert since his Colbert Report days. And when they showed up on his Late Show last night, they weren’t just there to do musical-guest duties. They did just fine as musical guests, of course, performing the vaguely skronky “Random Name Generator,” from last year’s album Star Wars. But Colbert also roped frontman Jeff Tweedy into doing a comedy bit. As the show ended, Colbert got into a mocked-up childhood bedroom and got Tweedy to sing him a lullaby, which turned into a whistling duet. It’s not exactly funny, but it is oddly charming. Watch both the performance and the lullaby below.

Star Wars is out now on Anti-/dBPM.