NBA star Kyrie Irving walked back on comments he made publicly saying the Earth is flat.

Irving, who was in Boston on Monday at the Forbes Under 30 summit, said he was “sorry” for the remarks and didn’t realize how his words would affect others.

“To all the science teachers, everybody coming up to me like, ‘You know I’ve got to reteach my whole curriculum?’ I’m sorry,” said Irving. “I apologize. I apologize.”

In February 2017, Irving was on a podcast and questioned whether the Earth was flat. He initially said he made the comments to start a conversation on how stories can go viral, but he later said he wasn’t sure if the Earth was round, according to the Associated Press.

“I do research on both sides,” Irving told The New York Times in June. “I’m not against anyone that thinks the Earth is round. I’m not against anyone that thinks it’s flat. I just love hearing the debate.”

At the summit, he chalked up his words to his interest in conspiracy theories.

“At the time, I was like huge into conspiracies,” Irving said. “And everybody’s been there.”