A camshaft phaser having a vane-type phaser having a central-position locking device having locking pins lockable in a locking slot stationary with respect to the stator and locking in the locking slot from different directions. A locking pin has a blocking portion and a flow-through pressure medium conduit, by which a fluid connection between two working chambers of different directions of action can be established or blocked in the different positions of the first locking pin. The working chambers-of the different directions of actions are capable of being short-circuited by a switching device. At least one pressure medium conduit fluidically connectable to the pressure medium circuit by the flow-through pressure medium conduit of the locking pin has a check valve therein which allows the pressure medium to flow into one of the working chambers whose volume is increased during a rotation of the rotor from either of the advance or retard stop positions toward the central locking position, while at the same time preventing backflow from the same working chamber.