Maybe completely ignore his self deprecating comments. Maybe whatever your usual reaction is to that gives him something... like fishing for a compliment. Ignoring his unwanted behavior may just make him drop it. I try to do that too.
Me: 44 W: 45 S: 11 Married: 15 Together: 18 BD: 9/29/2014 OM discovered: 10/16/2014 I left her behind: 12/14/2014