The non-inverting four switches buck-boost (FSBB) converter is a topology which has recently attracted considerable attention in the area of Photovoltaic (PV) module-integrated power electronics. Due to limitations in the switching speed of MOSFETs and delays introduced to avoid current shoot-through, the gain function of such converter exhibits a discontinuous behaviour at the transition from buck to boost operating mode and vice versa. The discontinuous gain is the cause of undesired transients in the PV voltage and PV power. This paper focuses on a solution for the gain discontinuity issue by operating the converter in buck and boost mode simultaneously during the transition. Particular attention is devoted to the duty ratio compensation technique employed when operating the converter in both modes, and a criteria to set the converter duty ratios during the transition is given. The methodology presented should come as an aid for those considering the FSBB converter topology as a candidate for PV module-integrated converters.