The Tigers re-signed Mattison to a minor-league contract Dec. 18 that includes an invitation to spring training, Evan Petzold of the Detroit Free Press reports.
Mattison was non-tendered by the Tigers last month, but he's now back in the organization and will be in big-league camp this spring. The righty reliever boasts a 32.8 percent strikeout rate in the minors but has been held back by a bloated 13.4 percent walk rate.