The Treaty of Melno (Lithuanian: Melno taika; Polish: Pokój melneński) or Treaty of Lake Melno (German: Friede von Melnosee) was a peace treaty ending the Gollub War. It was signed on September 27, 1422, between the Teutonic Knights and an alliance of the Kingdom of Poland and the Grand Duchy of Lithuania at Lake Melno (German: Melnosee, Meldensee; Polish: Jezioro Mełno), east of Graudenz (Grudziądz). The treaty resolved territorial disputes between the Knights and Lithuania regarding Samogitia, which had dragged on since 1382, and determined the Prussian–Lithuanian border, which afterwards remained unchanged for about 500 years.