A method for measuring the concentration of a gas component in a measuring gas. An absorption line of the gas component is varied as a function of the wavelength of the light of a wavelength-tunable light source within a periodically sequential scanning interval. The absorption line of the gas component is modulated with a frequency (f0). Modulated light is guided through the measuring gas onto a detector. A measurement signal generated by the detector is demodulated upon determining a harmonic (nf0) of the frequency (f0). A measurement result is produced by fitting a setpoint curve to the profile of the demodulated measurement signal. Both demodulated measurement signal and setpoint cure are filtered with the aid of the same filter function. The filter function is operative to suppress noise signal components of the demodulated measurement signal that disturb both signal components of the demodulated measurement signal and the setpoint curve.