By Ariana Bacle
Updated May 08, 2015 at 04:43 PM EDT
Credit: CBS

David Letterman used to sing Simon and Garfunkel’s “America” to his son, Harry—and while that sounds like a terribly sweet scene to watch, it couldn’t compare to First Aid Kit’s goosebumps-inspiring rendition of the song that they performed on Thursday’s episode of The Late Show.

Letterman introduced the Swedish duo, made up of sisters Klara and Johanna Söderberg, by talking about the last time he sang the song to his now 12-year-old son. “I read him the story, and I put him in the crib, and I said, ‘Harry, which song would you like to hear tonight?'” Letterman said. “And Harry said, ‘No song.’ And that was it.”

Simon and Garfunkel themselves once performed “America” on The Late Show with just a guitar to accompany their voices. First Aid Kit, though, brought in some strings for backup—a choice that made their performance all the more heavenly. And Letterman approved: “That was sweet,” he said after shaking their hands post-performance. “That means a great deal to me.”

First Aid Kit will be touring North America and Europe throughout the summer. See the full list of tour dates here.