A technique for calculating a location of a first vehicle is described. A method implementation of this technique comprises the steps of detecting, from the perspective of the first vehicle, a movement of a second vehicle relative to the first vehicle, determining, for the time of the relative movement, a location of the second vehicle based on the detected relative movement by matching the detected movement of the second vehicle against map data, measuring, for the time of the relative movement, a distance between the first and second vehicles, and calculating the location of the first vehicle based on the measured distance and the determined location of the second vehicle. The technique also comprises an apparatus, a computer program product, and a vehicle navigation system.