Koch was born December 12, 1924, but his tombstone at Trinity Church Cemetery in Upper Manhattan made him appear 18 years younger than he was -- December 12, 1942, was set in stone.
The company responsible for the etchings on the marker became aware of the mistake Monday. The transposed numbers were fixed Tuesday morning using composite granite, according to George Arzt, Koch's former press secretary as mayor and his spokesman until his death.
The birth and death dates were added within the past 10 days, according to an etching company representative.
Koch hired an inscriber after he purchased his tombstone in 2007. He was able to see the engravings were etched as he wished; however, there were no dates at the time, according to Arzt.
"Ed would have loved this attention and called the situation 'ridiculous!' " Arzt told CNN on Tuesday.
Koch was a U.S. congressman from 1968 until he ran for New York mayor in 1977. He served three terms as the city's 105th mayor, from January 1978 to December 1989.
Koch died of congestive heart failure on February 1. He was 88 -- despite what his tombstone temporarily calculated.