Police are warning people in central Somerset to be aware of fake currency in their pockets and wallets.
There have been reports this week of a number of counterfeit £10 notes circulating across the area.
A police spokesman warned that shops often do not check £10 notes as thoroughly as larger denominations.
Fakes can sometimes go unnoticed and at the moment shop staff and customers need to stay vigilant – or be caught out with worthless paper in their pockets.
Police say that on close inspection the counterfeits should be easily spotted. Many appear to be little more than just flimsy colour photocopies.
The initial notes have been spotted across the Mendips, including Shepton Mallet. There are fears they could also have been distributed at Street and Glastonbury.
Genuine notes are printed on a fine cotton weave, and have a watermark and metal thread running through them.
Under close scrutiny the detail of fake notes will look messy and lack the detail that can be seen in real notes. Genuine notes also have individual serial numbers, something forgers do not bother to try and replicate.
Anyone with any fears that they have been passed fake notes should contact their local station, on the special police line 101, or Crimestoppers on 0800 555 111.