"The Whole Country is Red" - except the designer left out Taiwan
A Chinese stamp pulled from circulation the day it was issued because it failed to show Taiwan as part of China has fetched a record price in Hong Kong.
The rare 1968 stamp was picked up at an auction by an unidentified buyer, for HK$3.68m (US$475,000, £290,000).
It features a worker holding a book filled with Mao Zedong's quotations and a red map of China in the background.
However, self-ruled Taiwan was left uncoloured. China sees the island as a renegade province of its own.
The stamp is entitled "The Whole Country is Red". Its sale sets a record price for a Chinese stamp.
Its designer, Wang Wei Sheng, who watched the hammer fall, said he had feared he would be punished for his mistake.
"For a long time I was really worried that I would be jailed," he told AFP news agency.
"Officials told me that it was a really big mistake, but in the end nothing happened."
Mr Wan and other designers had been commissioned to make a series of stamps during the Cultural Revolution, a decade-long period of mass political and social upheaval in China starting in the mid-1960s.
Taiwan split from China in 1949 at the end of a civil war and has been self-ruled since, but Beijing still considers the island as part of its territory awaiting reunification.