Refrigerant compressor for a hermetically encapsulated small refrigerator, which has a piston (20) guided in a piston bore (3) of a cylinder housing (1), the cylinder housing being frontally terminated using a valve plate (7) having a pressure opening (17) and a suction opening (16) and also being frontally provided with holes (5), which each have a thread. In order to adapt refrigerant piston compressors having screwed-on cylinder head in such a manner that an energy-efficient redesign of the structure cylinder cover-valve plate-cylinder housing is possible, the changes on the structure required for this purpose simultaneously being minimized, it is provided that a first clamping element (11), which is screwed into the holes (5), is provided, which contacts the valve plate (7) and presses it against the cylinder housing (1) in the area of at least a section of the piston bore wall (14) and has a pre-tension in the direction of the valve plate (7) in the screwed-on state, the clamping element (11) having a clamping section (13), which is located above the piston bore wall (14) in the installed position and has the shape of an imaginary projection of the piston bore wall (14) on the first clamping element (11).