McDonald’s is facing a class action lawsuit from plaintiffs who allege the fast food chain has long deceived customers about what type of meat is in the popular, limited McRib sandwich.

The lawsuit was filed late last month in the U.S. District Court for the Northern District of Illinois by eaters from California, New York, Illinois and Washington, D.C. who claim the sandwich is marketed as containing pork rib meat but actually has none.

The complaint alleges that despite the patty’s rib shape, the item’s name and price, the sandwich is actually made of lower-quality grounded up pork — from cuts like shoulder and tripe — not rib meat.

The company’s website claims the meat is a “pork patty” made of “seasoned boneless pork.”

“The name ‘McRib’ is a deliberate sleight of hand,” the lawsuit reads. “McDonald’s willfully, falsely, and knowingly omitted various material facts regarding the quality and character of the McRib — namely, that despite its name and distinctive rib-like shape, it does not actually contain any actual pork rib meat. McDonald’s knew these facts would be material to reasonable consumers but still chose not to disclose them.”

McDonald’s denied the lawsuit’s claims.

“This lawsuit distorts the facts and many of the claims are inaccurate,” the chain told NBC 5 Chicago. “Food quality and safety are at the heart of everything we do – that’s why we’re committed to using real, quality ingredients across our entire menu. Our fan-favorite McRib sandwich is made with 100% pork sourced from farmers and suppliers across the U.S. We’ve always been transparent about our ingredients so guests can make the right choice for them.”

McDonald’s debuted the McRib in 1981. After becoming a limited-time-offer, it’s sporadically appeared on menus since.