Abstract: A method for controlling a boost pressure of an engine, which includes a charging device including a compressor and a compressor bypass, the compressor bypass including a blow off valve for opening and closing the compressor bypass. A boost pressure control uses an actual boost pressure and a setpoint boost pressure as input parameters. A first compressor pressure ratio is ascertained based on a limit line from a compressor characteristic map and an engine absorption characteristic for the engine. A second compressor pressure ratio is ascertained based on the limit line, a mass flow, and a throttle characteristic curve for the blow off valve. A maximum permissible compression ratio for the compressor is ascertained from the first and second compressor pressure ratios. A maximum permissible boost pressure is ascertained as a function of the maximum permissible compression ratio. The boost pressure control is limited to the maximum permissible boost pressure.