A reflector sight (2) for a portable firearm has an optical system for generating a natural image of a target region, a display (4) for reproducing an electronic image of the target region created by an electronic image creation unit and a beam splitter cube (6) for overlaying the natural image with the electronic image of the target region reproduced by the display (4). According to the invention, the display (4) is arranged on a first flat face (10) of beam splitter cube (6), to which flat face a correction lens (12) is connected (12), the face (14) of which facing the display is convex, wherein a mirror lens element (18) is connected to a second flat face (16) of the beam splitter cube, the mirrored face (20) of which mirror lens element facing away from the beam splitter cube (6) is convex and aspherical and wherein the beam splitter cube (6), the correction lens (12) and the mirror lens element (18) form a correction block that consists of silica glass and/or.