Speaking at the annual Stanford Directors’ College on Tuesday, the San Francisco Chronicle reports that Mayer said that Kalanick might have been unaware of the problems with Uber’s sexual harassment and discrimination-prone culture because of how fast the company was growing.

“I just don’t think he knew,” she continued. “When your company scales that quickly, it’s hard.”

Mayer’s name has been floated as a possible replacement for Kalanick, but it’s not clear if the company has had talks with her yet, notes the San Francisco Chronicle. Kalanick stepped down last week after five of Uber’s major investors demanded his immediate resignation.