Britney Spears says her new book is the highest selling celebrity memoir in history

Britney Spears is thanking her fans for their support of her new memoir, The Woman in Me.

In an Instagram post shared Tuesday, October 24, the day of the book’s official release, Britney celebrated the accomplishment, noting the memoir has already made history.

“It’s happening,” Britney wrote in her caption. “My book is the highest selling celebrity memoir in history and it’s only day 1 !!! Thank you to the fans who have been so supportive !!! Love you all.”

While Britney says her book is the bestselling celebrity memoir of all time, the claim has yet to be confirmed by its publisher, Simon & Schuster.

If true, that would mean The Woman in Me has surpassed Prince Harry’s Spare, which was released in January. Spare currently holds the world record for the fastest selling nonfiction book of all time, with reported release day sales of over 1.4 million copies.

Britney’s book currently tops the Amazon and Barnes & Noble best sellers lists, though specific data about its first day sales are not yet available.