UPDATE with video, below Bill Maher couldn’t get so much as a chuckle out of his history professor guest tonight when the subject turned to dictators. Timothy Snyder, author of On Tyranny: Twenty Lessons From The 20th Century sat stonefaced as Maher read off a list of things about Donald Trump that remind him of Third World dictators.

“Yeah, right, so I’m not going to laugh at any of that,” Snyder said on HBO’s Real Time With Bill Maher, “because in your world it’s Third World dictators, but in my world…it’s the 1930s.”

To be fair, Maher’s roster didn’t seem intended so much as a comedy bit (that came in New Rules, watch below) but rather as a fun-poking checklist of Trump habits – putting names on buildings, hiring family members, holding rallies, hating the press, blaming minorities – but when he asked when Snyder when we can expect Trump to don military regalia, the Yale professor didn’t bite.

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“Picking out a group of your neighbors and citizens and associating them with a worldwide threat, that’s the 1930s,” Snyder said. “And what we have to remember about the 1930s, we think of Hitler and Stalin as supervillains but they’re not – they could only come to power with some form of consent.”

Snyder then turned to the audience, with Maher’s encouragement, to warn of what maybe comes next. “When a terrorist attack comes, you will not necessarily know who did it. What you can know is that certain kinds of leaders will use that to suspend your rights. During your fear and your grief you have to mobilize and protest for your own rights because the Reichstag fire is the oldest trick in the Hitlerian book. You cannot let that trick be played.”

After that, Maher’s feisty New Rules segment, in which he likened Trump’s campaign promises to infomercial blather, couldn’t quite maintain the drama. “No sense crying over spilt snake oil,” he consoled.

Also on tonight’s show: conservative pundit Matt Schlapp, MSNBC’s Chris Hayes, journalist and former Conservative British M.P. Louise Mensch and Max Brooks, the former SNL writer who wrote the World War Z book. (Brooks was filling in for scheduled guest who canceled, Congressman Ted Lieu).

Real Time hasn’t posted the Snyder clip online as of Saturday morning, but here’s the New Rules segment that followed: