Most of us use debit or credit cards to pay at all kinds of locations without much thought. But these cards, especially at high-traffic locations like ATMs and fuel pumps, pose a special risk. Hopefully you know to look for the danger signs of a compromised ATM (like a fake number pad). Recently, a new type of device has become popular for fraudsters to install on card readers at gas stations. These can steal your card info without you even noticing, and transmit the stolen details via Bluetooth.

If you want an extra measure of security against these attacks, you should install the free Android app Skimmer Scanner.

Open up this simple app, make sure you have Bluetooth enabled, and tap Scan. Your phone will then search for nearby Bluetooth devices commonly used to skim cards and alert you if there’s a compromised scanner nearby. It will generate a list of nearby Bluetooth devices, including those that are harmless like your car system and your smartwatch. When it’s done scanning, you’ll see if it detected any scam devices.

Of course, this isn’t foolproof. Just because it doesn’t find a device doesn’t mean that the card reader is safe. Also, if you find a device, remember that you may accidentally authenticate your device’s Bluetooth to it, which could identify your device to the criminals using it. Don’t try to remove any skimmers yourself — let the station employees know and they can take the appropriate action.

In all, this is a great app to keep around. Running a quick scan before you pump gas only takes a moment, and could save you from the annoyance of having your card stolen. Just don’t let your guard down because you have the app in your corner.