Walter will be promoted from Triple-A Worcester and appear in Thursday's game against Minnesota, Chris Cotillo of The Springfield Republican reports.
It's unclear whether or not Walter will be granted the start Thursday or follow behind an opener, but either scenario will allow for the 26-year-old lefty to make his first appearance in a major-league game. Walter has been rather unspectacular in Worcester this season, recording a 6.28 ERA and 1.67 WHIP through 61.2 innings.