Waymo CEO John Krafcik has announced that he’ll be stepping down from his role as CEO. Tekedra Mawakana, Waymo’s chief operating officer, and Dmitri Dolgov, the company’s chief technology officer, will work jointly as co-CEOs going forward.

Krafcik didn’t provide a detailed explanation for his departure or what he’s planning on doing next. “After five and a half exhilarating years leading this team, I’ve decided to depart from my CEO role with Waymo and kick-off new adventures. To start, I’m looking forward to a refresh period, reconnecting with old friends and family, and discovering new parts of the world,” he commented in a blog post announcing the move.

In a statement to employees obtained by CNBC, Mawakana and Dolgov said, “We’re committed to working alongside you to build, deploy and commercialize the Waymo driver and drive the success of our incredible team and this company. We’re energized by the road and opportunity ahead of us.”

Krafcik joined Waymo as its first CEO back in 2005, before it was its own branch of the company (or even before it was called Waymo), and he has led the division since. He’ll also be sticking around in at least some capacity as an adviser going forward. Before joining Waymo, Krafcik served as president and CEO of Hyundai’s American operations (in addition to a stint at automotive price comparison site TrueCar).

Waymo has come a long way since then: the company has been testing fully autonomous on-demand self-driving cars in Phoenix since 2018 through its Waymo One service (which it’s continued to ramp up in subsequent years). The company is also working on self-driving commercial trucks as part of its Waymo Via service.