A clamp for linking a mounting rail to a flange of a beam is disclosed. The clamp includes a lower base, an upper base, a connecting web, and a T-shaped back-gripping element, which is disposed at the lower base for gripping a rail opening of the mounting rail from behind. In the upper base, a threaded hole, which corresponds to the lower T-shaped back-gripping element, is provided for a clamping screw, with which the flange and the mounting rail can be pressed against one another when the lower T-shaped element grips a rail opening of the mounting rail from behind. In the lower base, a threaded hole, which corresponds to an upper T-shaped back-gripping element, is provided for a clamping screw, with which the flange and the mounting rail can be pressed against one another when the upper T-shaped element grips a rail opening of the mounting rail from behind.