A telescopic arm for a crane with a winch device provided with a wire, the telescopic arm comprising: - a telescopic boom assembly arranged to hold a pulley device for the wire at a tip of the telescopic boom assembly, - an adaptor comprising a first end pivotally connected to the telescopic boom assembly at a boom assembly pivot axle and a second end structured to be mounted to a crane boom of the crane, wherein a longitudinal axis A1 of the crane boom and a longitudinal axis A2 of the telescopic boom assembly extend in a common plane, and - a wire guide arranged between the winch device and the pulley device, the wire extending from the winch device via the wire guide to the pulley device, and the wire being guided by the wire guide in the region of the boom assembly pivot axle, wherein the wire guide further comprises a first wire guiding pulley with a first wire guiding wheel arranged to rotate around a first pulley axle, characterized in that the first end of the adaptor comprises a first part and a second part pivotally connected to the boom assembly pivot axle, wherein the first part and second part being symmetrically arranged on either side of the common plane, with a gap in between the first part and the second part forming a cavity in the adaptor arranged to be intersected by the common plane, when the telescopic boom assembly is mounted to the crane boom, - wherein the first wire guiding wheel is arranged in the gap between the first part and the second part and the boom assembly pivot axle is arranged as the first pulley axle around which the first wire guiding wheel is arranged to rotate; - wherein the wire guide further comprises a second wire guiding pulley with a second wire guiding wheel arranged to rotate around a second pulley axle in the common plane, and - wherein the first pulley axle and the second pulley axle are positioned in relation to each other such that the wire routed by the wire guide passes outside said cavity and between said first and second wire guiding wheels (26, 38). - a telescopic boom assembly arranged to hold a pulley device for the wire at a tip of the telescopic boom assembly, - an adaptor comprising a first end pivotally connected to the telescopic boom assembly at a boom assembly pivot axle and a second end structured to be mounted to a crane boom of the crane, wherein a longitudinal axis A1 of the crane boom and a longitudinal axis A2 of the telescopic boom assembly extend in a common plane, and - a wire guide arranged between the winch device and the pulley device, the wire extending from the winch device via the wire guide to the pulley device, and the wire being guided by the wire guide in the region of the boom assembly pivot axle, wherein the wire guide further comprises a first wire guiding pulley with a first wire guiding wheel arranged to rotate around a first pulley axle, characterized in that the first end of the adaptor comprises a first part and a second part pivotally connected to the boom assembly pivot axle, wherein the first part and second part being symmetrically arranged on either side of the common plane, with a gap in between the first part and the second part forming a cavity in the adaptor arranged to be intersected by the common plane, when the telescopic boom assembly is mounted to the crane boom, - wherein the first wire guiding wheel is arranged in the gap between the first part and the second part and the boom assembly pivot axle is arranged as the first pulley axle around which the first wire guiding wheel is arranged to rotate; - wherein the wire guide further comprises a second wire guiding pulley with a second wire guiding wheel arranged to rotate around a second pulley axle in the common plane, and - wherein the first pulley axle and the second pulley axle are positioned in relation to each other such that the wire routed by the wire guide passes outside said cavity and between said first and second wire guiding wheels (26, 38).