Twitter on Friday banned ads that deny the reality of climate change.

Twitter’s announcement on  Earth Day came as it tries to fend off an unwanted takeover bid by billionaire Elon Musk, who has said he thinks people should be able to say pretty much whatever they want on the platform.

“Misleading advertisements on Twitter that contradict the scientific consensus on climate change are prohibited, in line with our inappropriate content policy,” Twitter global sustainability manager Casey Junod said in a blog post.

“We believe that climate denialism shouldn’t be monetized on Twitter, and that misrepresentative ads shouldn’t detract from important conversations about the climate crisis.”

Twitter last year introduced a Topic feature to help users find conversations about climate change, and rolled out hubs of “credible, authoritative” information on an array of high-profile topics including the science backing climate change.

“We recognize that misleading information about climate change can undermine efforts to protect the planet,” Junod said.

“Now more than ever, meaningful climate action, from all of us, is critical.”

As tempting as access to Musk’s wealth may be, Twitter is not eager to be ruled by a billionaire known for shooting from the hip with little regard for the consequences.

The global one-to-many messaging platform is moving to prevent Musk from getting his hands on all of Twitter’s outstanding shares, signaling that worries about where he would lead the company outweigh the proffered payoff.