On Tuesday, Amazon announced it was raising its minimum wage to $15. People were ecstatic and with good reason. In the United States, Amazon directly employs 250,000 people with another 100,000 brought on as “seasonals,” the company’s term for the workers who flood its fulfillment centers during the holiday season. Some of them presently make as little as $10 per hour for grueling — sometimes fatal — work.

While $15 an hour is hardly enough to live a decent and dignified life in this country, it is going to make a world of difference for those who were making even less. As the second-largest private employer in the United States, Amazon’s raise may also benefit workers at other companies as it increases pressure on competing employers to raise wages in order to attract and retain workers in a tight labor market.

But even if a celebration is in order, there are details that should give pause to anyone concerned about worker power.

First, the announcement was quickly followed by reports that the company is scrapping stock awards and monthly bonuses for warehouse workers. According to Bloomberg, Amazon “informed those employees Wednesday that it’s eliminating both of those compensation categories to help pay for the raises.” While Amazon insists “the net effect” of the cuts in benefits alongside the raise will still be “significantly more total compensation for employees,” some calculate that the slashed benefits would cancel out “at least half” of the pay increase. Some workers assert they won’t come out ahead at all.

Then there’s the reality that Amazon, like many companies, classifies some of its workers as independent contractors. It’s increasingly reliant on its “Amazon Flex” program, which allows people to sign up and earn money for delivering packages to customers. While Amazon employs Flex drivers in all practical matters, technically they aren’t employees.

Amazon outsources liability for this program, making use of a legal loophole that allows it to evade the traditional responsibilities that would come with the employee/employer relationship — paying for vehicle expenses, such as maintenance and gas, or taking responsibility should a driver be injured on the job, for instance. While some drivers have sued the company over this classification, the law so far remains on Amazon’s side. This raise won’t apply to independent contractors.

Finally, although Amazon directly employs over 500,000 people worldwide, the wage bump is exclusive to the United States and the United Kingdom. This, more than anything else, complicates what would be a simple narrative of victory for workers. The past year has seen workers in Italy, Germany, Poland, and Spain escalate disputes with the e-commerce giant. During Prime Day, a holiday created by Amazon, workers walked off the job in Germany, Poland, and Spain. In Spain, some faced violent repercussions. The company appears to have no plans to give these workers raises.

Which gets to the crux of the problem. It’s a good thing, yes: It was won thanks to workers in Amazon’s fulfillment centers organizing around their working conditions; the Fight for $15, which has insisted for years that a $15 minimum wage is both ethical and feasible even as politicians insist otherwise; and Sen. Bernie Sanders, a long-time backer of worker organization and the demand for a $15 federal minimum wage who has lately used his massive platform to pick pro-worker fights with companies like Disney, McDonald’s, and Amazon. Such a coalition is a bright spot in a very dark era, and it’s a model of the bare minimum we’ll need to keep building working-class power.

However, “$15” is not the full slogan. It’s “$15 and a union.”

Without a union, Amazon workers cannot counteract the top-down system of governance that controls their lives. A structure where one man gets to decide whether hundreds of thousands of people will be able to feed their children or pay rent is intolerable. Raise or no raise, as it stands, Amazon workers cannot effectively contest the company’s grueling hours, its unsafe work practices, or its misclassification of employees. Jeff Bezos prefers the current setup: keep the workers powerless and avoid having to take them seriously or listen to them across a bargaining table as they explain how impossible it is to live a dignified life as an Amazon worker. No, that is unacceptable for King Bezos.

Which is why he does not want Amazon workers to unionize. That’s why the company is disseminating 45-minute anti-union videos. Bezos is worth around $164 billion — the richest man in modern history — and he knows just as well as his employees do where all that money came from: exploiting workers. Giving up unilateral power to direct Amazon’s profits into his bank accounts — or if circumstances necessitate it, to direct a few extra scraps to workers — is the last thing Bezos wants to do.

The watchword in the fiefdom of Amazon.com Inc. remains “union.” This raise is a concession from Bezos, one he felt was necessary to get the target off his back. All bosses know that too much heat can spark a fire, and Bezos was facing that possibility: Every horror story from within one of his facilities and every mention by Sanders of his negligence pushed workers closer to winning the case for unionization.

“Hopefully,” Bezos must think now, basking in the positive press that followed his decision to raise wages, “this will deflate the organizing.” Toss workers a bone and sleep more comfortably at night, think the new oligarchs. We shouldn’t be fooled by that. Amazon workers need a union; they cannot rely on Bezos’s largesse. He’d never have gotten where he is today if they could.

Just as Bezos looks out for himself above all else, workers should carry on doing the same: union, union, union.