The disclosure relates to a hydraulic unit of an electrohydraulic gas exchange valve control system of an internal combustion engine. The hydraulic unit includes a hydraulic housing having a receiving opening, a piston guide, and a slave piston. The piston guide is fastened in the hydraulic housing by way of self-staking with a wall of the receiving opening.
The piston guide includes an outer part that brings about the self-staking and an inner part that guides the slave piston. An inner surface of the outer part is radially interspaced from the outer surface of the inner part in an axial region of the self-staking and the outer part and the inner part are connected in an axially form-locked manner so that a first end section of the outer part facing the gas exchange valve is partially or fully formed into an outer circumferential recess of the inner part.