'We Are Young' hitmakers fun. have given one of their previously unreleased tracks to the new season of 'Girls' for use on its soundtrack.

The popular show, created by Lena Dunham who is dating member Jack Antonoff, returns to HBO on January 13 and fun.'s song 'Sight Of The Sun' features on it.

Frontman Nate Ruess admitted that the offering was originally intended to be on the band's latest album, 'Some Nights', but didn't make the cut because of an uncleared sample and he explained that they "got really dejected and put it away until Lena called."

Ruess added: "I ended up rewriting the chorus and actually like it better than the sample now! We recorded most of this in Italy on a day off from tour and I just remember us eating an Italian feast at the studio and barely being able to communicate with the engineers, which was kind of cool because it eliminated all small talk and put the focus into the song."

fun. are about to head out on tour across the U.S. and their dates are due to begin on January 17 in Vermont. The tour will end on February 16 in Nashville, Tennessee.

Listen to the track, entitled 'Sight Of The Sun', below: