Bookshops from Boston to Beijing are selling out of Order of the Phoenix even though it's only available in English at the moment.
After five million copies of the book were snapped up in the US on Saturday, the publisher has decided to print loads more.
It will bring the total of US copies to 9.3 million.
In China, 5,000 editions were snapped up, despite the language barrier and the fact that the book's quite expensive.
The country's intending to order at least another 5,000 copies, a Chinese book importer said.
If Chinese people want to read the book in their own language, they will have to wait until 1 October.
French people will have to wait even longer - until 3 December.
Internet sales for OOTP have also gone through the roof, with online retailer Amazon taking orders for 1.3 million books worldwide.
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