Paul McCartney's busy week continues. First he showed up for a couple of impromptu performances. Then he made a new video with some famous friends. Oh, and he also released an album -- his best in 30 years.

And now the superbusy ex-Beatle has remade his 1979 holiday single, 'Wonderful Christmastime,' with the a cappella group Straight No Chaser. The song shows up on their upcoming EP 'Under the Influence: Holiday Edition,' which will be released on Oct. 29.

According to Rolling Stone, Straight No Chaser's Don Nottingham said the collaboration is a dream come true. "The list of musical living legends starts with Paul McCartney," he said. "If you'd asked me five years ago – or even five months ago – what collaboration would be totally unfathomable for me, I would have said McCartney. To have him on a song with us is totally unbelievable and a true honor."

The new version basically replaces the primitive synths of McCartney's original song with a chorus of voices filling in for the instruments. McCartney, once again, takes lead on 'Wonderful Christmastime.'

Rolling Stone is also offering an exclusive listen to the reworked version of the holiday classic, if you want to take a listen.