Abstract: A door lock comprising a first thin plate having connecting channels secured to the side wall of the door jamb and a second thin plate having corresponding connecting channels secured to the side wall of the door adjacent its swinging edge in position for registration of its connecting channels with those of the first thin plate when the door is in its closed position. A locking pin is received through the connecting channels of both plates when they are brought into registration with each other to thereby hold the door in its closed position until the locking pin is withdrawn. The outwardly facing surface of the first plate secured to the door jamb and the surfaces of its connecting channels which face toward the swinging edge of the door when in its closed position are preferably coplanar to prevent those surfaces of the first plate's connecting channels from protruding into the swinging path of the door as it is opened and closed.