A collapsible fastener and method of making same for joining workpieces which fastener can be fabricated with a single machining operation aside from thread tapping. The fastener comprises a forged sleeve defined by cylindrical exterior and interior surfaces. The sleeve has a head at one end for bearing against one surface of the workpieces, internally threaded tail, and a shank extending between the head and the tail. A plurality of extruded grooves on the exterior surface of the shank are parallel to the axis of the sleeve. An extruded notch in each groove is at substantially the same distance from the head. When a mandrel is extended through the head and the shank and is threaded into the tail, by turning the mandrel the tail may be drawn toward the head whereby the shank splits into strips which fold at the notches.