The Pirates selected De Jong's contract from Triple-A Indianapolis on Sunday.
De Jong was added back to the 40-man roster and 26-man active roster following a two-week stint at Indianapolis after he was outrighted to the minors in May. Over his last five outings prior to his call-up, De Jong pitched to a 2.84 ERA, 1.89 WHIP and 7:5 K:BB in 6.1 innings for Indianapolis. He'll likely see most of his usage in lower-leverage spots while he's up with Pittsburgh.