The words 'Join the IRA' had been scrawled on the side of a building in Strabane, Co Tyrone.
But some bright spark decided to inject some positivity into the graffiti, altering it to read 'Join the library' instead.
Derry-born author and English teacher Brian McGilloway posted the picture on Twitter, prompting thousands of other users to retweet it and hundreds more to favourite it.
"Got to admire the Strabane kid with the cultural conscience who altered 'Join the IRA' graffiti to this," he said, adding that it had brightened up his week.
"Books beat balaclavas" and "Pity there's not more like him" were among the many, many responses.
Speaking to UTV, 'Strabanksy' confesses to not actually being a kid but rather a 28-year-old who was pushed into action in the early hours of last Wednesday by some rogue punctuation.
Once I saw how library fit so nicely around the original tag, I felt compelled to change it.
"I noticed the original graffiti on Tuesday and being a keen writer and grammar pedant, I was annoyed by the unnecessary apostrophe," he said.
"Strabane has an excellent library beside the Alley Theatre (I recently did a poetry reading there) - hopefully people take the advice and go and visit both premises."
With graffiti usually frowned upon at the best of times, Brian McGilloway said this instance had definitely managed to become a positive.
"I thought it was very witty and so incongruous for graffiti. Anything that encourages people to use libraries and read books can't be bad," he told UTV.