A hydraulic camshaft adjuster (1) having a rotor (2) and a stator (3) as well as a cover (4) which is situated in a rotatably fixed manner on the stator (3) and is separate from the stator (3), having a spring (11) designed as a spiral spring (10), the spiral spring (10) having an inner, first end (9) which is fixed on the rotor (2) in a form-locked manner and an outer, free end (13) which is fixed on the cover (4) in a form-locked manner, the second end (13) of the spiral spring (10) being located in a groove (17) present in the cover (4), the groove (17) extending in such a way that the second end (13) of the spiral spring (10) extends from a side of the cover (4) facing away from the stator (3) to a side of the cover (4) facing the stator (3).