daniel radcliffe harry potter'Harry Potter' star Daniel Radcliffe panicked at the prospect of J.K. Rowling added more books to the series, our friends at Celebuzz report.

"I could definitely write an eighth, a ninth book," Rowling told Oprah last October. "I think I am done, but you never know."

"I was worried!" Radcliffe told Celebuzz. "I texted her. I said, 'Look, is this true? Are you writing another book?!'"

Rowling kept Radcliffe waiting in agony (he'd texted her in the middle of the night) before responding. "She wrote back that she was so pleased with my performance in 'Harry Potter 7: Part 1' that as a reward, she promised to never write another book about Harry," Radcliffe said.

So was Rowling serious with Oprah or is the series truly closed?