A flashing member for a roof element, such as a roof window, said flashing member comprising: a first longitudinal element (110; 310) extending in a longitudinal direction, said first longitudinal element having a generally L-shaped cross-section with a first leg (112; 312) and a second leg, the first leg (112; 312) being adapted to be arranged against a side of the roof element raising from a plane of a roof in a mounted position, the second leg being adapted to be arranged to extend along said plane of the roof in the mounted position, the first leg and the second leg being joined at a corner of the L-shape, inner sides of the first leg and the second leg relative to the L-shape defining an angle of less than 180° and outer sides of the first leg and the second leg relative to the L-shape defining an angle of more than 180°, the inner sides constituting a concave side of the flashing member, a distal edge portion (116; 316) of the second leg opposite the corner being bent towards the concave side, and said second leg comprising a slit-shaped pocket (117; 317) with an opening towards the distal edge portion (116; 316) and a bottom towards the corner of the L-shape; and a second longitudinal element (120; 320) comprising a first side (121; 321) inserted into the pocket (117; 317) of the first longitudinal element (110; 310) and a second side (122; 322) opposite the first side (121; 321), said second side comprising a second edge portion (123; 323) which is bent towards the concave side, wherein the pocket (117; 317) has a depth (d) between its opening and its bottom, the second leg has a width between a distal edge thereof and the corner of the L-shape, whereby the second longitudinal element (120; 320) is positionable in a first mounted position in which the first side (121; 321) is at a vicinity of the bottom of the pocket (117; 317), in a second mounted position in which the first side (121; 321) is remote from the bottom of the pocket, and in a plurality of positions in between the first mounted position and the second mounted position, thereby providing an overall width of the second leg, including the second longitudinal element, that is adjustable to fit surrounding elements in an installation situation characterized in that said depth (d) of the pocket is more than half said width of the second leg. a first longitudinal element (110; 310) extending in a longitudinal direction, said first longitudinal element having a generally L-shaped cross-section with a first leg (112; 312) and a second leg, the first leg (112; 312) being adapted to be arranged against a side of the roof element raising from a plane of a roof in a mounted position, the second leg being adapted to be arranged to extend along said plane of the roof in the mounted position, the first leg and the second leg being joined at a corner of the L-shape, inner sides of the first leg and the second leg relative to the L-shape defining an angle of less than 180° and outer sides of the first leg and the second leg relative to the L-shape defining an angle of more than 180°, the inner sides constituting a concave side of the flashing member, a distal edge portion (116; 316) of the second leg opposite the corner being bent towards the concave side, and said second leg comprising a slit-shaped pocket (117; 317) with an opening towards the distal edge portion (116; 316) and a bottom towards the corner of the L-shape; and a second longitudinal element (120; 320) comprising a first side (121; 321) inserted into the pocket (117; 317) of the first longitudinal element (110; 310) and a second side (122; 322) opposite the first side (121; 321), said second side comprising a second edge portion (123; 323) which is bent towards the concave side, wherein the pocket (117; 317) has a depth (d) between its opening and its bottom, the second leg has a width between a distal edge thereof and the corner of the L-shape, whereby the second longitudinal element (120; 320) is positionable in a first mounted position in which the first side (121; 321) is at a vicinity of the bottom of the pocket (117; 317), in a second mounted position in which the first side (121; 321) is remote from the bottom of the pocket, and in a plurality of positions in between the first mounted position and the second mounted position, thereby providing an overall width of the second leg, including the second longitudinal element, that is adjustable to fit surrounding elements in an installation situation characterized in that said depth (d) of the pocket is more than half said width of the second leg.