Back in April, Chipotle proudly declared that it was the only major fast food chain in the country to contain an entirely GMO-free menu. Now, just four months later, a recently filed class-action lawsuit says that proclamation isn’t exactly truthful, accusing the fast casual restaurant of false advertising and deceiving diners into paying more for their food.

The class-action lawsuit [PDF], filed by a California woman in federal court in San Francisco, alleges that Chipotle violated the Federal Food, Drug and Cosmetic Act because its food labeling is false and misleading, and the company deceived diners into paying more for their food on the basis that it was GMO-free and “aligned with consumers’ ethical eating choices.”

According to the lawsuit — which aims to cover everyone who bought Chipotle in California since the April 27 “no GMOs” announcement — Chipotle has been selling itself to health-conscious consumers since at least 2009.

“Chipotle has carefully tailored its public image by marketing to healthy-lifestyle and environmentally conscious consumers that it knows are willing to pay premium prices for its food,” the lawsuit states.

The plaintiffs contend that Chipotle’s recent public statements do not accurately reflect the company’s practices.

“As Chipotle told consumers it was ‘G-M-Over it,’ the opposite was true. In fact, Chipotle’s menu has never been at any time free of GMOs,” the lawsuit states.

Among other things, the complaint claims that Chipotle continues to serve meat products that come from animals which feed on GMOs, including corn and soy.

The suit also asserts that the sour cream and cheese products used at the company come from dairy farms that feed animals with GMOs. Additionally, Coca-Cola and other soft drinks sold by the chain are made with corn-syrup that likely contains GMOs.

While the company’s advertisements don’t mention that GMOs may be found in its products, its website does contain notices that some of its products – including soft drinks and meat – may include GMOs.

In one instance, the company notes that “most animal feed in the U.S. is genetically modified, which means that the meat and dairy served at Chipotle are likely to come from animals given at least some GMO feed.”

However, the lawsuit claims these disclaimers are not good enough, noting that “Chipotle only discloses this information on its website because it knows its fast-food customers never need to visit Chipotle’s website to buy food.”

“Chipotle knows that its menu contains ingredients with GMOs, it takes no meaningful steps to clarify consumer misconceptions in its advertisements and on its billboards, both in stores and in print, which instead say ‘all’ of the ingredients used in its Food Products are ‘non-GMO,'” the suit states. “A ‘hipotle meal was, and remains, the very definition of a GMO meal.”

As a result of Chipotle’s conduct, the suit alleges, that customers are routinely deceived into buying the company’s food, or paying more for Chipotle products than they would have otherwise paid.

“Consumers today are very concerned about what they eat, and restaurants know that consumers place a premium on food that is considered to be healthy or natural,” an attorney representing the proposed class-action said in a statement. “Chipotle’s advertising in its stores should have accurately informed customers about the source and quality of its ingredients and should not mislead consumers that they are serving food without GMOs when in fact they are.”

The lawsuit seeks unspecified damages for the class.

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