Even in the late 1990s, Johnston said that he had lived most of his life with "a moving 10-year life expectancy" because of his early bout with rheumatic fever, but he remained in good health until he was more than 90 years old. He died in 2012; he was 92. Johnston was survived by his wife of 64 years, Mary Ella, and their four children, as well as several grandchildren and great-grandchildren.