Sure, the title tells you to have a “merry little Christmas.” But it’s a complicated message. The actual, original lyrics of the song make the vaguely depressing song undoubtedly one of the darkest tunes ever, not to mention Christmas carol.

The song first gained widespread popularity in 1944 with an appearance in the big-screen musical Meet Me in St. Louis. Set in 1904, just before the start of the St. Louis World’s Fair, Esther Smith (Judy Garland) sings the song to her five-year-old sister (Margaret O’Brien), upset that their father is planning to move to New York right around Christmas and also just before the start of the World’s Fair in their hometown.

But despite the song fitting into the circumstances of the musical quite well, the song was written in 1943 by composer Hugh Martin. His original take on the song was extremely dark, deeply sad…and befitting the fact that the U.S. was deep into World War II. Among some of Martin’s original lyrics: “Have yourself a merry little Christmas / It may be your last / Next year we may all be living in the past.” Both cast and crew of Meet Me in St. Louis balked at the song, particularly the depressing lyrics. He protested at first, but ultimately wrote some new lines. Notably, those lines noted above became the now familiar “Have yourself a merry little Christmas / Let your heart be light / Next year all our troubles will be out of sight.”
But remaining in the song was a lyric near the end of the song that worked for both the separated family in Meet Me in St. Louis as well as the audience missing friends and family serving abroad: “until then we’ll have to muddle through somehow.” While that lyric is still occasionally sung, it’s frequently omitted in favor of “hang a shining star upon the highest bough.” Frank Sinatra ordered the change from Hugh Marin in 1957. He reportedly told the songwriter to “jolly up” the song before he could sing it for his album A Jolly Christmas.