What if you changed the locks? At the very least it would force him to ask for something ahead of time. Or how about getting stickers that say "PROPERTY OF BRIT PLEASE CALL XXXXXXXXX TO BORROW"?
Or stop by his place to reclaim the items?
Okay you probably don't want to do any of these things. Just getting a little feisty in my neck of the woods today
At the very least it would force him to ask for something ahead of time. Or how about getting stickers that say "PROPERTY OF BRIT PLEASE CALL XXXXXXXXX TO BORROW"? 
