For a sustainable future, efficient solar energy harvesting and storage is required. Solar hydrogen production from photoelectrochemical water splitting is a promising technology and, in particular, cuprous oxide photocathodes are interesting photoelectrodes due to their high efficiency and low cost. However, chemical instability inhibits practical application of such devices. This work reports a novel strategy for protecting cuprous oxide from photocorrosion, wherein a thin SnO2 overlayer enables increased stability over previous reports utilizing TiO2 protective layers. Performance and stability are influenced by the film thickness, post-deposition steam treatment, and the nature of the heterojunction interface. Stability over 57 h of sustained photoelectrochemical water reduction, maintaining 90% of initial photocurrent, is achieved.