Abstract: The invention concerns a tensioning device for the cable of a cable window lifter which is mounted in a drive bracket pulled up and down along a guide rail by means of a cable wound around an actuation drum. One cable end is solidly joined to the drive bracket whereas the other cable end is connected by a directional lock to the drive bracket. This directional lock compensates any cable elongation taking place within the cable actuation system by means of spring action. The tensioning device of the invention is characterized by providing further compensating means. This further compensation is needed in the event of excessive stresses exerted on the cable actuation system in the closed window position which results in a spurious cable elongation caused thereby. It also eliminates this compensation when this excess stress is no longer present.