The song is in the key of D-flat major. The Beatles recorded the song in C major but the master take was sped up in order to raise the key by one semitone at the insistence of McCartney. Martin remembers that McCartney suggested this change in order to make his voice sound younger. McCartney says, "I wanted to appear younger, but that was just to make it more rooty-tooty; just lift the key because it was starting to sound turgid."