Leah Jeffries, far left, with co-stars Walker Scobell, center, and Aryan Simhadri.
CNN  — 

The author of “Percy Jackson and the Olympians” has called out fans for being racist, after backlash against the casting of a Black actress in the upcoming television adaption of the popular book series.

Actress Leah Jeffries was cast to play Annabeth Chase in the Disney+ adaptation of Rick Riordan’s beloved novels. In the books, Chase is described as White, and some fans have criticized the casting of Jeffries for not visually aligning with the books.

Riordan was quick to defend Jeffries and condemn the haters in a blog post published Tuesday.

“You are judging her appropriateness for this role solely and exclusively on how she looks. She is a Black girl playing someone who was described in the books as white,” he wrote. “Friends, that is racism.”

Since the casting announcement was revealed last week, Riordan said Jeffries has been on the receiving end of racist bullying and other online harassment. In his post, Riordan called these comments “out of line” and demanded they stop. Still, most of the response to the casting announcement has been positive, he said.

“Leah brings so much energy and enthusiasm to this role, so much of Annabeth’s strength. She will be a role model for new generations of girls who will see in her the kind of hero they want to be,” he wrote.

On Twitter, Riordan also started the hashtag #LeahisOurAnnabeth, which was trending on the website by Tuesday afternoon.

“Percy Jackson and the Olympians” is a middle-grade series of novels first published in 2005, which follows a neurodivergent child who finds out he is the son of Poseidon, the Greek god. Disney released two movies based off the series – “Percy Jackson & the Olympians: The Lightning Thief” in 2010 and “Percy Jackson: Sea of Monsters” in 2013. A premiere date for the Disney+ series has yet to be announced.