Abstract: A pressure cooker is disclosed having a safety interlock including a resilient gasket interposed between flat sealing surfaces of a receptacle and a cover, and configured to form a seal against the surfaces when they are spaced by a first distance, and to prevent formation of the seal when the surfaces are spaced by a second, smaller distance. The receptacle and cover are provided with interlocking lugs which are engageable in two different conditions to determine the first and second distances respectively. The gasket comprises an annular body having inwardly directed, axially diverging leg portions terminating in lip portions to seal against the sealing surfaces, and has faces with peripherally spaced bosses engageable by the sealing surfaces when at the second distance to decrease the divergence of the leg portions and so prevent seal formation. Y-shaped, V-shaped, and W-shaped cross sections for the gasket are shown.