Starting when Passover begins on Friday night, Jews who are keeping kosher for the holiday must forgo foods with wheat, corn and other grains for the eight-day festival, severely restricting their diet. But one luxury is not out of reach: Coca-Cola.

The Atlanta-based soda maker provides a kosher-for-Passover version of its mainstay cola, identifiable by its yellow cap. Unlike most commercial sodas in the U.S. that are sweetened with corn syrup, this concoction uses sugar, helping it pass muster for those avoiding grains—and making it popular among those who say they prefer the flavor.

Hipsters and observant Jews alike are largely indebted to the efforts of one Orthodox rabbi eight decades ago. Rabbi Tuvia Geffen, Lithuanian-born but residing in Coke’s Georgia hometown, noticed that, of all the dietary restrictions of Passover, staying away from the soda was proving particularly difficult for his congregants. Before the holiday rolled around in 1935, responding to popular demand, he investigated the ingredients of the soft drink.

“Because it has become an insurmountable problem to induce the great majority of Jews to refrain from partaking of this drink,” Rabbi Geffen wrote in his rabbinical ruling. “I have tried earnestly to find a method of permitting its usage. With the help of God, I have been able to uncover a pragmatic solution.”

The solution was, it turned out, relatively easy. This was before the use of corn syrup, but the ingredients still sometimes included grain sugars; so Coca-Cola assured Rabbi Geffen that they would exclusively use cane sugar during Passover as well as scrap one other minor ingredient that the rabbi deemed not to be kosher. And with that, Rabbi Geffen pronounced Coke to be kosher.

The dramatic development was announced in a letter to TIME published in the May 13, 1935, issue, sent by one Samuel Glick of Atlanta. Glick was following up on a TIME article about the Jewish Passover celebration that had been published the previous month:

In connection with your interesting article on the celebration of Passover (TIME, April 29), you may be interested to know that, for the first time. Atlanta orthodox Jews were allowed to drink Coca Cola during this solemn season. With the approval of Atlanta rabbis, special Coca Cola bottle caps were stamped with the Kosher symbol and signs denoting the same were displayed in soda fountains. The drink was not altered in any way.

Read the 1935 story about the Passover celebration: Passover and Easter

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Write to Noah Rayman at noah.rayman@time.com.