In this paper we show that the PI passivity-based control (PBC) for power converters developed in [1] can be properly modified in order to guarantee global asymptotic stability of the closed-loop system even in case of inaccurate knowledge of the equilibrium to be stabilized. The proposed modification consists of the inclusion of a leakage in the integral action that, viewed in suitable incremental coordinates, acts as a damping term that helps to compensate the error induced by the imprecise knowledge of the equilibrium. Interestingly, with an appropriate choice of the parameters, the controller can be interpreted as a modulation index/power droop controller. The theoretical results are validated by simulations on a DC/DC boost converter.