A modular rounded corner piece for forming rounded corners of a pool. The modular rounded corner piece may include a plate portion and a liner receptor portion. The liner receptor portion may include a channel formed by a top wall and a bottom wall. The channel may align with a pool liner receptor slot in the coping around the perimeter of the pool. Thus, a continuous liner receptor slot may be formed around the interior circumference of the pool for receiving an edge of a pool liner thereinto. The modular rounded corner piece may be installed on the pool sidewall to provide a gapless alignment between the liner receptor on the pool sidewall and the liner receptor in the rounded side of the corner plate.