A device for changing the relative angular position of a camshaft with respect to a crankshaft of an internal combustion engine, wherein the drive element is rotatably mounted with respect to the crankshaft and is driven by the camshaft. Between the drive element and the camshaft at least two hydraulic chambers are formed, wherein the hydraulic chambers can be pressurized with a pressurized fluid in order to set a defined relative rotational position between the drive element and the camshaft. The device includes a housing element, wherein a pressure reservoir having a pressure chamber for pressurized fluid is arranged on the housing element and wherein the basic form of the pressure reservoir is substantially cylindrical. The pressure reservoir is disposed on the housing element in such a manner that the cylindrical lateral face thereof abuts a lateral portion of the housing element, wherein at least one fluid connection is formed between the housing element and the pressure chamber of the pressure reservoir.