A phase setter for adjusting the rotational angular position of a cam shaft relative to a crankshaft of an internal combustion engine. The phase setter includes a stator; a rotor which together with the stator forms a first and second pressure chambers; a control valve featuring a pressure port, and first and second working ports; a feed for the inflow of pressure fluid to the pressure port, a first connecting channel connecting the first pressure chamber to the first working port, and a second connecting channel connecting the second pressure chamber to the second working port; and a reflux valve device acts in the feed and includes a valve structure extending annularly around the rotational axis and has one or more spring tongues or can be axially moved to restrict backflow of pressure fluid through the feed more significantly than the inflow of pressure fluid to the pressure port.