The invention relates to an oscillating-motor camshaft adjuster having a hydraulic valve, which has two working ports. These two working ports each have a standard opening axially adjacent to one another and an opening for the utilization of pressure peaks as a consequence of camshaft alternating torques. A hydraulic pressure can be guided from a supply port to the working port to be loaded, while the working port to be relieved of pressure is guided to a tank port. In order to also keep the control performance high in the case of internal combustion engines with very greatly fluctuating camshaft alternating torques, it is proposed according to the invention that a position of hydraulic valve can be controlled proportionally, in which the pressure peaks of the working port to be relieved of pressure are blocked relative to the supply port and the working port that is to be loaded.