The Brewers recalled Koenig from Triple-A Nashville on Saturday.
Koenig has appeared in five games for the Brewers this season, allowing two runs (one earned) on nine hits and two walks while striking out four over 8.2 innings. The 30-year-old southpaw will return to the Brewers' bullpen, while right-hander Corbin Martin was optioned to Triple-A Nashville in a corresponding move.