Oakland, CA—Burger King is introducing a version of the Whopper made with a vegetarian patty from Impossible Foods, according to the New York Times.

TheTimesnotes that veggie burgers have had some success already: Carl’s Jr. has been selling burgers made by Beyond Meat since January; White Castle has been selling sliders with Impossible Foods patties since late last year. But, theTimessays, Burger King has 7,200 locations, which would more than double the number of locations where the Impossible burger is available.

That said, it won’t be in all 7,200 locations immediately. It’ll initially be available, according to theTimes, at 59 restaurants in the St. Louis area—but if everything goes smoothly, the company has plans to quickly expand it to every location in the country.

TheTimesquoted Fernando Machado, Burger King’s chief marketing officer, as saying: “People on my team who know the Whopper inside and out, they try it and they struggle to differentiate which one is which.”

Health-wise, theTimesnotes that the Impossible Whopper will have the same amount of protein as the regular Whopper, with 15% less fat and 90% less cholesterol. That said, it won’t be vegan—it’ll be prepared precisely the same way as the regular Whopper, with mayonnaise.

For more, including background on Impossible Burgers,go here.