An adjustable corner fitment for a roof and a method and apparatus for making the same are provided. The adjustable corner fitment may be comprised of a top membrane portion and a base membrane portion. The top membrane portion may have a cutout that may extend from a side of the top membrane portion. The base membrane portion may have four-sides. The first side of the base membrane portion is preferably connected to the second side of the base membrane portion at a first angle greater than 90 degrees, and the third side of the base membrane portion is preferably connected to the fourth side of the base membrane portion at a second angle greater than 90 degrees. It is preferred that the top membrane portion and the base membrane portion are made from thermoplastic olefin (TPO) material or polyvinyl chloride (PVC) material.