The Tigers reinstated Farmer (groin) from the 10-day injured list Thursday.
Farmer had been on the shelf since Aug. 10 with a left groin strain, but he was able to quickly move past the injury. The Tigers designated Carson Fulmer for assignment to clear a spot on the active roster for Farmer, who has been one of Detroit's top setup men this season with a 2.84 ERA, 1.11 WHIP and four holds over seven appearances.