To expand access to its self-driving cars, Waymo is teaming up with an unlikely partner: Uber.

The companies announced a “multi-year strategic partnership” to make Waymo rides available on the Uber app for users in Phoenix, Arizona. The news is somewhat surprising given that Uber and Waymo were locked in a tense legal battle over stolen trade secrets several years back.

“This integration will launch publicly later this year with a set number of Waymo vehicles across Waymo’s newly expanded operating territory in Phoenix, and will include local deliveries and ride-hailing trips,” the companies said in a blog post.

They’re also describing the partnership as a win-win for both companies. Waymo—a subsidiary of Google’s parent Alphabet—gets to tap Uber’s large user base. In return, Uber can offer robo-taxi rides, years after it sold off its own self-driving business. (That said, Uber is still working on autonomous taxis through a partnership with Motional, a joint venture between Hyundai and Irish-American automotive supplier Aptiv.)

Currently, Waymo is offering self-driving rides through its own mobile app, Waymo One. But it only has about 100,000 downloads, along with a 3.6 star review, on Google Play. In contrast, Uber has been downloaded over 500 million times and has maintained a 4.7 star review.

The two companies previously feuded back in 2017 after Waymo accused a former employee of stealing its trade secrets and giving them up to Uber. The ensuing lawsuit demanded the court suspend Uber from its autonomous vehicle research until the case was settled. But a year later, Uber reached a settlement that involved giving up a 0.34% stake, valued at $245 million, to Waymo. Uber also named a new CEO, Dara Khosrowshahi.

Both companies still compete for the same riders as Waymo gradually expands its self-driving cars to more cities. One big question is whether Uber will offer Waymo rides in additional areas outside Phoenix. The company didn’t immediately respond to a request for comment.