Former Con-way Freight drivers aren’t going down without a fight. Warehouse workers and truck drivers in Connecticut and Illinois voted on Wednesday to join the International Brotherhood of Teamsters. The call for union representation came after workers complained about low salaries and poor benefits at XPO Logistics Inc (XPO), which acquired Con-way Freight for $3 billion in September 2015. XPO now has groups of unionized employees in five states and is the third-largest freight company in America.

This week’s votes added 201 XPO workers to the union. This is far less than the 44,000 U.S. workers that XPO employs but, despite their small numbers, these victories for the Teamsters are a push in the right direction for advocates of workers’ right. Since acquiring Con-way a year ago, XPO has had two rounds of layoffs including the closure of seven freight terminals. Reports earlier this from the UK claim that XPO forced warehouse workers to work unpaid overtime by paying them a set monthly salary and then threatening disciplinary action if they didn’t “flex up” their hours when needed.

Workers could have another reason to fear for their jobs. In Europe, self-driving trucks are already being tested. This technology would reduce or remove the burdensome labor cost which today accounts for the bulk of a freight charge. A unionized workforce would make transitioning to self-driving trucks difficult or near impossible, much like how dockworkers’ unions made the transition from break bulk shipping to containerization so difficult for freighters 50 years ago. So, while a unionization might save jobs for workers, it comes at the cost of shareholders’ return. XPO’s stock opened 2% lower yesterday than Wednesday’s close and has continued to decline since.