President Harry Truman’s parents agreed their son’s middle name should honor his grandfather, but they were not in agreement about which one: Anderson Shipp Truman or Solomon Young. They decided that “S” would honor both, so they christened him “Harry S. Truman,” with “S” being his complete middle name.

When Chief Justice Vinson administered the presidential oath of office to Truman on April 12, 1945, he began by asking Truman to repeat the words, “I, Harry Shipp Truman, do solemnly swear…” The new President chose not to make a fuss about it, but simply corrected the name when he said, “I, Harry S. Truman, do solemnly swear….”

Since “S” is not an abbreviation, it is technically not correct to place a period after it when writing the President’s name. The Harry S. Truman Library and Museum in Independence, Missouri consistently uses a period, however, out of respect for the fact that the President wrote his middle name with a period:

If there is any question on the matter, it should properly be settled by the man from Missouri, who is so well identified with the words, “The Buck Stops Here.”

Read more fun facts about Harry Truman.