Thielbar signed a minor-league contract with Detroit on Tuesday, Mike Berardino of the St. Paul Pioneer Press reports.
Thielbar last appeared in the majors with the Twins in 2015. The lefty reliever owns a 2.74 career ERA over 98.2 major-league innings. His 2016 and 2017 seasons were spent with the independent-league St. Paul Saints, where he threw 91 innings with a 2.18 ERA. The weak Tigers' pitching staff gives the 30-year-old southpaw at least an outside shot to break camp with the big-league team.