A wrapper (310) for a smoking article comprises a sheet material extending in a first direction (24) in which the wrapper (310) is wrapped around a smoking article and a second direction (20) perpendicular to the first direction (24). The wrapper (310) further comprises a window (312) in the sheet material, the window (312) having a perimeter. Any linear segment of the perimeter forming an angle of less than 10° with respect to the second direction (20) has a length of less than 0.5 millimeters, and any curved portion of the perimeter having a continuum of tangents each forming an angle of less than 10° with respect to the second direction (20) has a length of less than 0.5 millimeters. Such linear segments and curved portions of the perimeter are spaced apart by a distance of at least 0.5 millimeters along the length of the perimeter. The perimeter includes at least one linear segment forming an angle of less than 10 degrees with respect to the second direction (20) and having a length of less than 0.5 millimeters. The window (312) has a width of at least about 2 millimeters.