Mariah Carey's "All I Want For Christmas Is You" and Irving Berlin's "White Christmas" are two of the most popular and beloved Christmas songs of all time. And they share the same chord progression — either intentionally or accidentally — that gives them a sound that we now instinctually associate with the holiday season.

Vox delves into this musical tidbit, via journalism professor and music nerd Adam Ragusea, who wrote about the phenomenon of this chord progression for Slate two years ago. He calls "the most Christmassy chord of all" the "minor subdominant, or 'iv,' chord with an added 6" or "You might also analyze it as a half-diminished 'ii' 7th chord," and it comes up in both songs.

He also notes that Carey was clearly trying to evoke the 60's with her song, and stylistically it very similar to Phil Spector's "Christmas (Baby Please Come Home)" from his 1972 Christmas album, originally released in 1968.

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