This probably isn’t what the United Nations had in mind when it established the International Day of Peace: Burger King is asking McDonald’s to join forces to create a “McWhopper.”

In full-page newspaper ads Wednesday, Burger King said it’s calling for a truce with McDonald’s so that they can create a mashup of their most famous burgers—the Big Mac and the Whopper. Burger King says it wants to serve the concoction for a single day at a popup location in Atlanta, a midway point between the headquarters of the two chains.