A surgeon performing an appendectomy forgot one important step, according to a lawsuit filed in New York.

Removing the appendix.

William McCormack, 43, of Bronxville, returned to the hospital a year later with abdominal pains only to discover his appendix had never been removed in 2013, UPI reported.

He's now suing Lawrence Hospital and the surgeon who was supposed to have taken it out.

According to the lawsuit, the doctor removed a "yellowish mass" from McCormack's stomach instead.

McCormack's attorney claims the doctor realized his mistake but ignored it.