During his last years Munn lived in Tacoma, Washington in a house he had built himself. He did his writing either in his living room or in the attic room that constituted his library. During this time he was working on an additional volume of the Merlin series to be called "The Sword of Merlin", which he did not live to finish. He was befriended at this time by the young writer W. H. Pugmire, who was influenced by Munn's work.