Sheryl Sandberg has a message for male managers: it’s high time to #MentorHer.

The Facebook COO’s corporate feminism initiative LeanIn.org has launched a campaign encouraging men in positions of power to sponsor women. The #MentorHer movement was inspired by the results of a poll that LeanIn.org conducted with SurveyMonkey, which revealed that 30% of male managers are uncomfortable working alone with a woman—double that from before the #MeToo movement kicked off last fall.

Among the poll’s findings are that the number of men uncomfortable with mentoring women alone has almost tripled to 16%, meaning that one in six male managers now think twice about engaging in an activity many workplace experts think is crucial to female corporate success. In the wake of the Harvey Weinstein sexual harassment allegations, which have claimed the scalps of prominent men like NBC host Matt Lauer and casino mogul Steve Wynn, high-ranking bosses are also five times likelier to hesitate before going on a work trip with a female subordinate.

The discoveries made by LeanIn.org aren’t that surprising. In recent months, a number of men have voiced support for the so-called Pence Rule. This refers to a commitment made by Vice President Mike Pence, who reportedly refuses to eat alone with a woman that he’s not married to. Many women say that this is unfair, since men overwhelmingly occupy managerial positions in companies. By refusing to socialize with women, this restricts the opportunities females have to advance. Others also note that this takes a particularly low view of male self-control, since the vast majority of men don’t sexually harass their female subordinates.

Also readSoledad O’Brien tells Moneyish how Maria Shriver mentored her through a pregnancy

“Men vastly outnumber women as managers and senior leaders, so when they avoid, ice out, or exclude women, we pay the price,” wrote Sandberg in a recent Facebook post.

“Men who want to be on the right side of this issue shouldn’t avoid women. They should mentor them.”

Hence #MentorHer, which has already signed up corporate head honchos like Sandberg’s boss Mark Zuckerberg and LinkedIn founder Reid Hoffman, who’ve pledged to mentor women junior to them. Also joining the crew are Unilever chief Paul Polman and Disney head Bob Iger, arguably the most powerful media mogul today.

“We need to end sexual harassment in all its forms. We need to hold perpetrators accountable – and the enablers who make excuses or look the other way,” Sandberg wrote. “But that is not enough. We also need to focus on getting more women into positions of power.”