It all began innocently enough, as these things often do.

Andy Mientus, a Broadway performer (who also plays the baddie in The Flash) posted an Instagram pic of himself holding up a handwritten sign on which he describes himself as “an out bisexual (seriously)”.

#ghostlightproject #BeALight A photo posted by @andymientus on Jan 19, 2017 at 7:47am PST

The sign, which didn’t sit well with some crampy online troll, reads:

I am an out, bisexual (seriously) theater-maker. I fight for diversity in ALL its forms, in all aspects of theater-making (casting, creative, administrative), as a means to evaluate underrepresented voices.

So far, so empowering.

But that’s when the aforementioned Instagram joker named ahmedkillzone decided to let the bi-phobia flow:

Bisexuality don’t [sic} exist. People are gay or straight if he in a relationship with a man he is gay this how I see it.

Related: Broadway’s Hottest Bisexual Has An Important Message For All You Bi-Deniers

Fortunately, Mientus wasn’t about to take all this bi-phobic blowback lying down.

He responded:

Are you devoid of sexuality when you are single? Are people only gay or straight if they are in relationships? Furthermore, have you ever considered that (gasp) not all relationships are monogamous?”

Take that, ahmedkillzone.

And while you’re at it, take this, too: