This paper addresses the problem of stabilizing voltages in DC microgrids given by the interconnection of Distributed Generation Units (DGUs), power lines and loads. As in (Tucci et al., 2016), we propose a decentralized control architecture where the controller of each DGU can be designed in a Plug-and- Play (PnP) fashion by solving a local Linear Matrix Inequality (LMI) problem. However, differently from (Tucci et al., 2016), when a new DGU issues a plug-in request, we no longer require that neighboring units update their local controllers in order to account for new electrical couplings. Indeed, a key feature of the novel approach is that the design of a local controller requires only the knowledge of the dynamics of the corresponding DGU. The proof of closed-loop asymptotic stability combines properties of graph Laplacians, structured Lyapunov functions and LaSalle invariance theorem. Theoretical results are backed up by simulations in PSCAD.