Abstract: In a dust cover (6) for the brake cylinder (1) of a disc brake with a ring-shaped boot (7), with a fixing torus (8) at a first end of the boot engaging an annular groove (9) in the piston (3) of the brake cylinder (1) and with a stiffening lining in the shape of a ring (11) which is at least partly surrounded by the material of the boot (7) and which urges the second end of the boot (7) against the inside wall (12) of a ring-shaped recess (5) in the front side (4) of the brake cylinder (1) said second end of the boot (7) forms a unilaterally open, ring-shaped bag into which said ring (11) is inserted. Within said bag the ring (11) is formed with perforations (14) which are penetrated by the material of the boot (7). A radial collar (13) of the ring (11) which projects out of said bag constitutes a surface of abutment for an assembly tool.