A cooling channel cover for a one-piece piston of an internal combustion engine, the piston having a closed cooling channel that runs around inside the piston crown, at the level of the piston ring band, and a ring-shaped recess provided between the piston ring band and the piston shaft. The piston shaft is connected with the piston hubs suspended on the piston crown. In such a piston, an easy to assemble cooling channel cover is achieved by a one-piece plastic / spring steel ring that is U-shaped in cross-section, having a ring bottom and an outer shank around the circumference, molded onto the ring bottom and angled off radially to the outside, and an inner shank around the circumference, angled off radially to the inside. The plastic ring has a first radial division having a mouth width and a second radial division, opposite the first division, which does not separate the radially angled outer shank that runs around the circumference, to form a film hinge for radial deflection of a ring shank formed by the film hinge.