Trader Joes has been sued over peanut butter pretzels.

The snack is one of the most popular sold by the grocery chain, but now Trader Joes is being sued by Maxim Marketing, which claims it invented the peanut butter-filled snack in the 1980s and supplied Trader Joes with it for over 25 years.

But Joes reportedly switched to ConAgra foods for the pretzels and cut Maxim out of the deal. Maxim Marketing is also suing ConAgra for "breach of contract and also alleging the existence of a peanut butter pretzel monopoly."

Maxim says this has cost it 9 million dollars' worth of peanut butter pretzel revenue a year, and essentially pushed them out of the peanut butter pretzel business.