The invention relates to an arrangement for clamping a warp beam tube or the like to a square rod, in which a flange is fixed on the axial end of the beam tube, the flange including a square axial opening for the reception of the square rod. The flange is clampable fast by at least one clamping screw to the corresponding axial end of the square rod. For providing a central clamping-in not subject to the danger of loosening, the flange is constructed as a clamping ring which includes at least one slit extending through from the square opening to the outer circumferential surface of the clamping ring. The slit is bridged by at least one tightening screw and its width is reducible by a tightening of the tightening screw.