A device is provided for determining a mass flow of a first gas flowing in a flowing channel of an internal combustion engine of a motor vehicle. The device includes: sound transducers arranged at respective ends of a measuring path for providing sound signals, a temperature sensor for determining a temperature of an overall mass flowing in the flow channel, and an evaluation unit arranged downstream of the sound transducers. The evaluation unit is capable of carrying out the following: determining a flow rate of the overall mass and a speed of sound based on delay times of the sound signals, determining an overall mass flow based on the flow rate, the temperature, and a pressure of the overall mass in the flowing channel, ascertaining a proportion of a second gas flowing in the flow channel at a temperature above 10° C. and based on the speed of sound and the temperature, and correcting the overall mass flow to obtain the mass flow of the first gas.