You'd think that Twitter trolls would have learned not to tangle with JK Rowling by now.

But no, they keep on popping up - and she keeps on cutting them down again.

The Harry Potter author gave us one of her best-ever comebacks after a cynical soul had taken issue with her opinion on the Syrian refugee crisis.

.@Lukekocura I'd type a longer retort, but these diamond buttons really hurt my fingers. pic.twitter.com/RJ19nIMd94

— J.K. Rowling (@jk_rowling) September 4, 2015

She had written: "If you can't imagine yourself in one of those boats, you have something missing. They are dying for a life worth living. #refugeeswelcome"

And her hapless critic added: "Said the millionaire on her gold iphone in her mansion"

Rather than address the facetious comment head-on, she responded with an hilarious put down instead.

"I'd type a longer retort, but these diamond buttons really hurt my fingers."

Strangely, her critic has failed to respond to her comeback.