Lighting device (2, 3, 4) for illuminating interiors in buildings or outdoor installations, wherein the lighting device (2, 3, 4) is configured for mounting in a substantially right-angled corner region of the interior, of the outdoor installation or of some other object, having the following features: a) a luminaire holder configured for securing in the substantially right-angled corner region, wherein the luminaire holder has at least a first securing surface for securing to a first corner region surface and a second securing surface for securing to a second corner region surface, wherein the first and second securing surfaces (211, 221) of the luminaire holder are arranged substantially at right angles to one another, b) a luminaire cover composed of at least partly light-transmissive material, wherein the luminaire cover is configured for securing to the luminaire holder, c) wherein a receptacle space for receiving at least one illuminant of the lighting device, in particular an LED strip, is formed by an interspace between the luminaire holder and the luminaire cover, characterized in that the lighting device (2, 3, 4) furthermore has a first wing, at which the first securing surface is formed, and a second wing, at which the second securing surface is formed, wherein the wings (21, 22) are connected to one another by way of a connecting section and wherein a) the first wing has a first base section, which is adjacent to the first securing surface towards the second wing, wherein the first securing surface is angled relative to the first base section by an acute angle (α 1), in particular an angle in the range of 1 degree to 8 degrees, and/or b) the second wing has a second base section, which is adjacent to the second securing surface towards the first wing, wherein the second securing surface is angled relative to the second base section by an acute angle (α 2), in particular an angle in the range of 1 degree to 8 degrees. a) a luminaire holder configured for securing in the substantially right-angled corner region, wherein the luminaire holder has at least a first securing surface for securing to a first corner region surface and a second securing surface for securing to a second corner region surface, wherein the first and second securing surfaces (211, 221) of the luminaire holder are arranged substantially at right angles to one another, b) a luminaire cover composed of at least partly light-transmissive material, wherein the luminaire cover is configured for securing to the luminaire holder, c) wherein a receptacle space for receiving at least one illuminant of the lighting device, in particular an LED strip, is formed by an interspace between the luminaire holder and the luminaire cover, a) the first wing has a first base section, which is adjacent to the first securing surface towards the second wing, wherein the first securing surface is angled relative to the first base section by an acute angle (α 1), in particular an angle in the range of 1 degree to 8 degrees, and/or b) the second wing has a second base section, which is adjacent to the second securing surface towards the first wing, wherein the second securing surface is angled relative to the second base section by an acute angle (α 2), in particular an angle in the range of 1 degree to 8 degrees.