Abstract: The invention relates to a sheet flashing member for a frame structure of a roof window or a similar roof penetrating building structure that comprises adaptable corner segments. The sheet flashing member comprises a sheet section (40) and first and second corner segments (20, 30). At least one of said corner segments at a surface thereof comprises at least one indication (22, 32, 34, 38), a visible indication or a weakening section, indicating a pattern, such that at least a part of the sheet section may be separated from the remaining part of the flashing member along the indication, which allows an adaptation of the corner segment by selecting between two different configurations for the corner segment e.g. whether it is to be used between a window and the surrounding roof or between two neighbouring windows.