The much-anticipated Finding Dory movie is out in less than a month and now we know its official theme song.

Sia was asked to deliver a cover of the Nat King Cole classic "Unforgettable," and the "Chandelier" chanteuse delivered a stunning rendition of the standard that she debuted live on The Ellen DeGeneres Show. The song is particularly perfect for a movie about Dory and the blue tang fish's infamous short-term memory condition.

"When I asked our next guest to sing the theme song to Finding Dory, I was thrilled that she said yes," DeGeneres (who voices Dory) told the audience before Sia began. She talked with Sia afterwards telling the singer, "I can't imagine anyone else doing this song. Thank you so much for doing this for Finding Dory."

Sia adorably responded by saying that she wanted to do it because "Dory's story makes me teary." True dat.

Look out for Finding Dory to open on June 17 and an expected studio version of Sia's "Unforgettable" to drop sometime before then. Check out all the must-watch blockbusters hitting theaters this summer right here.