Apple's digital jukebox, the iPod, is flying off shop shelves in the run-up to Christmas and Santa's helpers are struggling to keep up.
The iPod has proved a big-hitter this year
"The demand is certainly outstripping supply," said Mike Khalfey, department store John Lewis' electronics buyer.
Apple says it is working flat out to keep up with sales, but some shops are having to take post-Christmas orders.
It says it had shipped more than 1.3m of the small, white gadgets to shops all over the world by October 2003.
"We are getting shipments once or twice a week but we are selling them almost as fast as they come in," Mr Khalfey said.
An Apple spokesperson said it was doing all it could to increase production, but the demand meant some people may be disappointed on Christmas Day.
The iPod comes in three guises, but Mr Khalfey said the most popular model had been the mid-range one with 20Gb of storage space.
Apple senior vice president Ron Johnson was quoted as telling a US newspaper that an iPod was being sold in Apple stores worldwide every 10 minutes in the run-up to Christmas.
The iPod has had a good year in 2003, with two top technology magazines voting it as one of the country's favourite bits of consumer technology.
In a recent Stuff magazine readers' poll, it was voted best gadget of the year.
But it was narrowly beaten by the Pentax Optio S digital camera as the top tech toy by T3 magazine readers.
The iPod can carry up to 10,000 tunes, which users can download from online music websites, or transfer from CD collections. It can also store photographs and other types of files.