The police force in charge of security for the royal wedding has urged well-wishers in Windsor not to throw confetti.
Thames Valley said the tradition posed a "potential security risk" during the Prince Harry and Meghan Markle's carriage procession but was also a "bit of a pain to clean up".
The force said: "Please do not throw confetti or any other items at any time during the day, particularly during the procession.
"It poses a potential security risk and it's a bit of a pain to clean up!"
They added: "We hope everyone enjoys the day."
Crowds in central London threw confetti during the Duke and Duchess of Cambridge's wedding day in 2011.
Prince William and Prince Harry also showered their father Prince of Wales and stepmother the Duchess of Cornwall with confetti as the newlyweds left Windsor Castle on the evening of their wedding in 2005.
The brothers had also scrawled "Just married" and "Prince and Duchess" along with hearts and "C+C" in white pen on the windows of the car and had attached red, white and blue balloons on one side, and silver heart balloons on the other.
The confetti - ivory and pink freeze-dried delphinium petals - had been specially ordered by William and Harry.
A massive police operation is under way in Windsor with a 'ring of steel' surrounding the town centre for the wedding at St George's Chapel on Saturday.
Some 100,000 people are expected to travel to the Berkshire tourist destination in the hope of catching a glimpse of the bride and groom.
It is the largest ever police operation in the history of Thames Valley Police.