The Duluth Police Department has put out a Facebook post warning people of an increase in counterfeit bills. There has been an influx of 5, 20, and 100 dollar bills that are not legitimate in the Duluth area. The Duluth Police Department is asking that if you suspect the use of counterfeit bills, that you call 911 right away.

There’s some easy ways to detect counterfeit bills. According to the Secret Service Official Website, you can look for the watermark on the 2004 style Federal Reserve notes (FRNs) that will be visible from either side when held to light. Also on the Secret Service website, it says you can tell on 10, 20, 50, and 100 dollar bills of the 2004 style FRNs that they will have “color-shifting ink that shifts from copper to green as the note is tilted 45 degrees.”