Time synchronization plays a crucial role in every distributed system. This becomes more critical if we consider Wireless Body Area Networks (WBANs) composed by several motes which interface different sensors for the health status monitoring. The star-topology is commonly used in such application and sometimes it is necessary to squeeze the number of employed boards, having also the master node to expose some sensors. In this paper we discuss in detail the need and the issues introduced by the inclusion of the master in the synchronization procedure, and propose a routine to guarantee the complete master/slave synchronization.