The quasi-steady-state photoconductance (QSSPC) technique is well established in both research and industry for the study of crystalline silicon (c-Si) wafers passivated by thin-films for photovoltaic applications. Other methods to passivate c-Si wafers, involving liquids such as HF or iodine-methanol have also been reported. In this case the QSSPC setup needs a re-calibration to avoid effect of the containers' thickness on the measured photoconductance. In this paper, the dependence of the QSSPC output values on the distance between the sample and the stage (lift-off) is studied through both analytical simulation and experimental results. We provide a simple correction law in order to retrieve the true effective lifetime with no need to change the factory calibration.