A Shanghai artist has been detained for comparing Chinese president Xi Jinping to Adolf Hitler as well as an anus. Dai Jianyong, a street photographer best known for making what he calls a “chrysanthemum face“—the flower is a slang term in Chinese for anus—was detained on criminal charges today, according to the advocacy group Chinese Human Rights Defenders (CHRD).

Dai had posted photos online of t-shirts, suitcases, and coke cans decorated with a photoshopped image of Xi with a mustache, making a similar face. Although the mustache is not an explicit visual reference to the German dictator, online commentators observed that Xi resembled Adolf Hitler. (Some Chinese activists critical of the leader’s more draconian measures against dissidents have taken to calling him Xitele, a Chinese translation for Hitler that uses Xi’s surname.) Dai has been arrested for “creating a disturbance” and faces up to five years in prison.

Contemporary Chinese artists have typically gotten a longer leash than political activists, so long as they don’t cross certain lines like directly criticizing Chinese communist party leaders or depicting Mao Zedong too irreverently. Works by artists such as Ai Weiwei and the Gao brothers have been banned in China for those reasons, but other artists have been free to criticize the commercialism and inequality of socialist China and even censorship.

Now, under Xi, the environment for artistic freedom is tightening considerably. ”It has gotten worse, and Dai’s detention shows that humor, an expression of speech, is also under attack,” Wendy Lin, Hong Kong coordinator for CHRD, told Quartz.

Last year, the Beijing Independent Film Festival was shut down after organizers received warnings from officials to cancel. At least 16 artists were detained in the lead up to the June 4 anniversary of the Tiananmen crackdown or because of their support for pro-democracy protesters in Hong Kong. According to CHRD, three of these artists are still in detention, including a poet who was quickly arrested after he tweeted a photo of himself holding an umbrella in solidarity with Hong Kong’s “Umbrella Movement” demonstrators.

Over the past few years, artists based in Songzhuang, a village in suburban Beijing that has become a hub for young provocative artists, have been forced to cancel exhibitions and events, according to Lin. ”Suppressing dissent of any kind has become the norm,” Lin said.