A rotary operated latch of the "lift and turn" fastener type is disclosed having a cam action in the handle such that when the handle is moved to a latched position, it provides a pull on the pawl to compress a door or panel against a door or panel frame, or its gasket, to provide a tight seal. An over-center action prevents accidental release. A slot and pin arrangement prevents moving the handle to a latched position, except when the pin and slot are aligned. While the pawl and handle are normally rotatable relative to a sleeve in the door or panel which carries the mechanism, the pin and slot are so located as to be incapable of sufficient axial relative movement to move the handle into a latched position, except when the pawl is rotatably positioned for movement into a latched position.