This invention relates to a connector (1) for connecting a dialysate port (31) of a hemodialysis machine with a dialysate-carrying line. The inventive connector (1) has a recess (6, 6′) with a shift element (3) on the end (4) which accommodates the dialysis machine port (31), whereby the shift element (3) is accommodated in the recess and is displaceable between a first position and a second position perpendicular to the direction of the lumen (8) on this end (4). The shift element (3) does not pass through the lumen (8) in the first position. In the first position, the lumen (8) is constricted so that the connector (1) with the shift element (3) can be placed on the dialysate port (31), and in the second position it can be locked on the dialysate port (31) by means of an undercut (30) thereon. The inventive connector is suitable for production as a disposable item in comparison with the widely used Hansen coupling. At the same time, a simple and reliable connection of a dialysate-carrying line to a dialysate port of a hemodialysis machine is possible, and does not require any structural measures on the dialysis machine itself. (FIG. 3b)