The invention relates to a spindle gearbox (1) of an electric seat drive, comprising a gearbox housing (2) for mounting a worm gear (3) and a worm, the worm meshing with the worm gear (3), a threaded spindle (4, 5) connected to the worm gear (3), a first lid (6), and a second lid (7), wherein the first lid (6) and the second lid (7) are fastened parallel to one another on the gearbox housing (2). The threaded spindle (4, 5) is guided through the first lid (6), and the first lid (6) is fastened on the gearbox housing (2) independently of the second lid (7).