A method for functional monitoring of an apparatus for variable setting of a cylinder compression in a reciprocating-piston internal combustion engine is described, including ascertaining a value of an engine parameter which is indicative of an engine position of the internal combustion engine at a defined cylinder compression; comparing the ascertained value with a further value of the engine parameter; and determining, depending on a result of the comparison, whether the apparatus for variable setting of the cylinder compression is functioning correctly.