Twitter will strengthen rules rules to prevent sexual harassment and abuse on its platform, the social media company said Monday in an email to the collection of safety advocates, researchers and academics it uses help set its policies. There will also be harsher penalties for misconduct.

The new guidelines include immediately and permanently suspending the accounts of anyone who posts or is the source of non-consensual nudity. Twitter’s definition of non-consensual nudity will be expanded to include photos that are taken covertly.

Third parties will now be able to report unwanted sexual advances from one user to another. Previously, only those directly involved in the matter could do so.

Twitter also promised to publish new rules adding hate symbols and imagery to its definition of sensitive media.

The changes come on the heels of a series of tweets from CEO Jack Dorsey Friday pledging to limit the number of bullies and harassers using Twitter.

The micro-blogging platform faced intense criticism last year after it temporarily banned actress Rose McGowan last year for a tweeting out contact information for person she said was connected with Harvey Weinstein, who has faced accusations of sexual assault from McGowan and others.