The White Sox claimed Zach Stewart off of waivers, MLBTR has learned. The Pirates had designated Stewart for assignment one week ago to create 40-man roster space for Jeff Karstens.

This marks the second time in two years that the White Sox have acquired Stewart. They traded for him and Jason Frasor in July of 2012, sending Edwin Jackson and Mark Teahen to Toronto. Stewart posted an 8.58 ERA with 4.8 K/9 and 1.0 BB/9 in 35 2/3 innings for the White Sox and Red Sox this past season. The Red Sox traded him to Pittsburgh in November, but he never threw a pitch for the Pirates.