The lack of control over downstream assets can hinder universities' ability to extract rents from their inventive activities. We explore this possibility by assessing the relationship between invention generality and renewal decisions for a sample of Canadian nanotechnology patents. Our results show that general purpose inventions enjoy a longer legal life. Although private sector organizations renew their patents at a higher rate than universities, the gap between the two sectors decreases as invention generality increases. However, there is little indication that the most general purpose inventions owned by universities survive for longer than the ones owned by private sector organizations.