About 3,200 machinists are set to walk off the job around midnight after members voted down a deal that would’ve raised wages by 20% and boosted retirement contributions. The union last went on strike in 1996, with the stoppage lasting 99 days.

Employees at Boeing’s St. Louis defense factories rejected a contract offered by the aerospace giant Sunday afternoon, setting the stage for about 3,200 workers to walk off the job starting at midnight—the first strike the company has faced at its St. Louis defense hub since 1996.

Boeing (NYSE:BA) is facing the prospect of its first strike in nearly 30 years at its defense manufacturing facilities near St. Louis, after union members rejected a revised labor agreement. Roughly 3,