Examples disclosed herein relate to front-to-back registration of a printed content onto a print medium. In one example, a trigger signal generated by a sensor upon detection of a trigger mark on a first surface of a print medium is received. The trigger mark includes a leading edge and a trailing edge, wherein the leading edge and the trailing edge are non-parallel. Based on the trigger signal, a distance of the trailing edge from a point on the leading edge is determined. Once determined, a measure of lateral wander of the print medium with respect to the print path is obtained. The measure of the lateral wander is determined by comparing the distance between the leading edge and the trailing edge, with a threshold value.