On Monday, Mumford and Sons returned to the Tonight Show with Jimmy Fallon to perform their new jam “Guiding Light”.

Frontman Marcus Mumford sat down with Fallon, where he let slip that their new album Delta isn’t actually finished. (If you’re keeping track, the album is set to be released November 16.) He also went into detail about how each band member contributes songs, the first album he bought and what it was like to forget Bruce Springsteen lyrics – while singing with the Boss himself.