Say goodbye to Tumblr porn.

Starting Dec. 17 all adult content will be banned from the blogging platform — though the algorithm used to flag pornographic content is already malfunctioning, banning images as innocuous as someone’s bare neck.

Forbidden images and videos will include anything that “shows real-life human genitals or female-presenting nipples” and any photos, footage or illustrations “that depicts sex acts.”

Exceptions to the adult content ban include nude classical statues, political protests that feature nudity, breastfeeding photos, and illustrations and art with nudity — so long as they aren’t of sex acts.

But users said the deployment of Tumblr’s new mathematical formula was censoring random nonsexual posts, like Victorian-era diagrams, cartoons and an image of someone’s neck.

The new policy, announced Monday in a post by CEO Jeff D’Onofrio, was quickly blasted by users who started tweeting their disapproval with the hashtag #tumblrisdead.

“Tumblr just signed it’s own death warrant. Do they not know their niche in the social media landscape?” wrote @BrettGleason. “The place served as a great site for underground artists of all content – including those who like SEX.”

Since 2007 when it was founded, users flocked to the site in part for its relative lax rules on nudity compared to other social media platforms.

“Good thing about Tumblr was the mix of images representing ALL ones life interests. Now a key FREE visual aid to daily life activity is being banned from Tumblr, it won’t fulfill an important part of life…RIP Tumblr & uniqueness,” tweeted @london_rocklad.

Added a user named Skylar: “It’s a shame, tumblr was the last place on the internet that wasn’t restrictive. Very sad loss for the internet on the 17th.”

The platform is also popular with sex workers, who now worry what censorship will do to their community and how it’ll affect business.

“Tumblr was a site that allowed adult content; embraced it,” Daisy, an 18-year-old sex worker from Mississippi, told The Daily Beast. “There’s a whole community there of people that are all doing the same thing.”

“To lose that is losing a lot more than my sales,” she added. “To see people that I talk to everyday get deleted, [to see] my own blog deleted, it really is heartbreaking.”

The announcement of the adult-content ban comes just days after the Tumblr was removed from Apple’s App Store over images of kiddie porn that made their way onto the site.

Tumblr removed the content showing child sex abuse and said it has a “zero-tolerance policy,” leading some users to believe the adult-content ban is also in response to that incident.