Police in the Alpes-Maritimes département are taking no chances this Halloween, issuing a statement with detailed information about what costumes are deemed safe.
"Have fun, be imaginative, scare people - but don't terrorize!" the police wrote. "Dangerous toy guns are forbidden."
Basically, the officers have said that any outfit that includes a fake firearm is unacceptable.
In case it wasn't clear enough, they send out a series of pictures containing "acceptable" and "unacceptable" costumes (we've included a selection below).
And it's no surprise they're taking the matter seriously.
In February this year, officers in Nice launched a massive manhunt after witnesses reported seeing a man cruising around town armed with a Kalashnikov.
It turned out to be a 17-year-old high school student dressed for a party as tough guy actor Mr T, known for his roles in 80s TV show The A-Team and Rocky III.
Halloween takes off in France
The French have only given Halloween a lukewarm reception since it was officially introduced in 1999, but a new YouGov poll suggests the festivities are taking off.
Indeed, over 30 percent of 18-44-year-olds are expected to take part in some kind of celebrations on Saturday, with around 30 percent of 25-34-year-olds considering making specific purchases for the day.