MINNEAPOLIS (AP) — A small group of Wisconsin-based video game workers can vote to form what could be the first union at a major U.S. video game publisher, a labor board official ruled.

A regional director of the National Labor Relations Board on Friday ordered a May election for quality assurance workers at Activision Blizzard’s Raven Software, which develops the popular Call of Duty game franchise.

The unionization campaign by 21 employees at Raven’s office in Middleton, Wisconsin, has been part of a broader internal shakeup at Activision Blizzard, a Santa Monica, California-based gaming giant with roughly 10,000 employees worldwide.

The company has come under fire from the government and some shareholders, and it recently settled a federal civil rights lawsuit over allegations that management ignored sexual harassment and workplace discrimination against female employees.

Microsoft in January announced its plans to buy the company for nearly $69 billion and has said it wouldn’t interfere in unionization decisions.

Friday’s decision by Jennifer Hadsall, a regional NLRB director in Minneapolis, rejected Activision’s push to have the election encompass a wider category of Raven workers — which could have diluted the unionizing group’s vote.

Activision Blizzard earlier in April said it would be converting nearly 1,100 part-time quality assurance jobs into full-time workers and raising their hourly wages to at least $20.