He began his lexicographical work in 1970 with the Dictionary of Old English, supported by the Canada Council. Work on this project was still ongoing at the time of his death, leading to the university becoming a centre of the study of Old English. He was one of the first to see the advantages of using computers for lexicographical work. Declining health in later life prevented him taking up the appointment as Director of the Centre for Medieval Studies. He died of cancer in Toronto on 27 May 1983 at the age of 42.