There is a growing body of knowledge about the behavioral and neural correlates of cross-modal interactions in the perception of motion direction, as well as about the computations that underlie unimodal visual speed processing. Yet, the multisensory contributions to the perception of motion speed remain largely uncharted. Here we show that visual motion information exerts a profound influence on the perception of auditory speed. Moreover, our results suggest that this influence is specifically caused by visual velocity rather than by earlier, more local, frequency-based components of visual motion. The way in which visual speed information affects how fast we hear a sound move can be well described by a weighted average model that takes into account the visual speed signal in the computation of auditory speed.