Britain’s new 50 pence coin has sparked debate after a renowned author pointed out the absence of a certain punctuation mark on the piece.

On January 31, the Royal Mint launched three million coins with the slogan “Peace, prosperity and friendship with all nations” to mark the United Kingdom’s exit from the European Union.

Novelist Philip Pullman called for a boycott against the new coin ahead of its release, citing what he perceived as a grammatical error.

“The ‘Brexit’ 50p coin is missing an Oxford comma, and should be boycotted by all literate people,” Pullman wrote on Twitter.

The Times Literary Supplement editor Stig Abell also wrote, “The lack of a comma after ‘prosperity’ is killing me.”

According to the Associated Press, Oxford commas should be used whenever necessary to clarify.

“We say: If omitting a comma could lead to confusion or misinterpretation, then use the comma. But: If a comma doesn’t help make clear what is being said, don’t use it. ‘The flag is red, white and blue’ is clear.”

Writing for The Conversation, Associate Professor Roslyn Petelin of the University of Queensland’s School of Communication and Arts said the absence of Oxford comma is not the coin’s only shortcoming.

“Does ‘Peace with all nations’ make grammatical sense? No. Does ‘Prosperity with all nations’ make grammatical sense? No,” Petelin wrote.

“As admirable … as Pullman might be in advocating for the use of the Oxford comma on the coin, it’s clear this coin has committed more than one crime against the rules of grammar.”

This article originally appeared on Over60.