In Vehicular Ad Hoc Networks (VANETs), nodes periodically share beacons in order to convey information including identity, velocity, acceleration and position. Truthful positioning of nodes is essential for the proper behavior of applications, such as formation of vehic- ular platoons. Incorrect position information can cause problems like increased fuel consumption, reduced passenger comfort, and in some cases even accidents. In this paper, we design and evaluate Vouch: a secure proof-of-location scheme tailored for VANETs. The scheme leverages future deployment of fiſth generation (5G) wire- less network roadside units, and is able to operate using different overhead constraints. Through simulations using an adversarial model, we show that Vouch can detect position falsification attacks while incurring in low overhead.