Peters will start Sunday's game against the Brewers, Jason Mackey of the Pittsburgh Post-Gazette reports.
He threw five innings Aug. 7 at Triple-A but has not pitched more than three innings in any other appearance since going six innings July 10. All told, Peters has a 3.71 ERA, 1.31 WHIP and 63 strikeouts in 53.1 innings through 13 appearances at Triple-A. It's unclear if he will be making a spot start or if he could stick in the rotation going forward.