Who knew Splenda could be so sour? Heartland Food Products Group, which owns Splenda in the United States, is suing Dunkin’ Donuts, alleging that the coffee chain has been deceptively passing off its own light-yellow sweetener packets as Splenda, according to a report in the weekly Indianapolis Business Journal. The lawsuit, filed this week in Indianapolis court, around where Heartland is based, says that Dunkin’ Donuts has committed trademark infringement and false advertising. This is a lot of drama, it seems, over a no-calorie sugar substitute—sucralose, in this case—but Heartland means business, and they may indeed have a case. A big issue with trademark infringement is likelihood of confusion, and it seems somewhat likely that a customer could mistake Dunkin’ Donuts’ sucralose sweetener packets for Splenda, since they are the same color.

Dunkin’ Donuts stopped doing business with Heartland in the spring, according to the lawsuit cited by the Indianapolis Business Journal, around when they began using an off-brand sucralose made in China, with its own pink-and-orange company logo emblazoned on the exterior. Apparently Heartland got a bunch of emissaries to go out to more than 70 Dunkin’ Donuts in the country to see what was going on, and they weren’t happy with what they found. The lawsuit states that a big chunk of Dunkin’ Donuts employees said they use Splenda when they really just give out fake Splenda. 

Dunkin’ Donuts, which—quelle horreur!—also uses blue and pink generic sweetener packets, doesn’t seem to have much luck with sweeteners. In 2011, a woman with diabetes sued the chain after it accidentally put real sugar in her coffee and she went into diabetic shock. That's serious, but it’s hard not to think that Heartland is overreacting here. Perhaps employees knew they were giving out fake Splenda but didn’t want to confuse their customers, or waste time explaining that, yes, it was basically Splenda since it contained the same primary ingredient, but no, it wasn’t exactly Splenda—much in the same way a waiter might bring you a Pepsi if you’ve asked for a Coke.