A method for detecting GNSS spoofing by way of GNSS receiver of a localization system is disclosed. The GNSS receiver includes an antenna for receiving GNSS signals. The GNSS signals are emitted by at least one GNSS satellite and are received by the GNSS receiver in such a way that each GNSS signal is shifted by a frequency difference. The method includes a) receiving a GNSS signal by way of the antenna, b) measuring the frequency difference between the frequency of the GNSS signal emitted by a GNSS satellite and the frequency of the GNSS signal received by the antenna, c) determining the rate of change of the frequency difference by using motion change information relating to the GNSS receiver, d) checking if the determined rate of change corresponds to a rate of change characteristic of satellite signal reception, and e) detecting GNSS spoofing if the determined rate of change does not match satellite signal reception.