Publish/subscribe (pub/sub) proliferates loose coupling and is touted to facilitate mobility. The inherent loose coupling even allows existing applications to be transferred to mobile environments, if an appropriate infrastructure support is available. However, existing pub/sub middleware are mostly optimized for static systems where users as well as the underlying system structure is rather fixed. In this paper, we analyze the necessary steps to support mobile clients with publish/subscribe middleware. The REBECA content-based pub/sub service is extended to accommodate to physically mobile clients, offering a location transparent access to the middleware without degrading the previously guaranteed quality of service. The transparent access allows existing applications to be seamlessly transferred from a static to a mobile scenario without having to adapt client applications.