Now that we’re in 2015, hoverboards exist—just as Back to the Future II predicted. But they obviously haven’t been perfected quite yet. According to reports, real-life hoverboards might explode.

Thousands of the futuristic motorized self-balancing devices (also known as self-balancing scooter or eboards) were seized by British authorities at UK ports and borders because they didn’t pass basic safety checks. Many were at risk for catching fire, or outright blowing up.

The authorities at UK ports and borders have reported a huge spike in the number of the items arriving in recent weeks, with testing revealing serious safety issues with the plug, cabling, charger, battery or the cutoff switch within the board. Many of the hoverboards seized and sent for testing were found to have non-compliant plugs without fuses, increasing the risk of the device overheating and exploding.

“We suspect that most of these products are being imported for onward sale domestically as Christmas approaches,” Toby Harris, the Chair of the National Trading Standards, warned. “We urge customers to be on their guard when purchasing this Christmas.”

National Trading Standards has since released a tip sheet for people who buying hoverboards, which advises purchasers to only buy from reputable sources and to never leave their hoverboard unattended while charging.

The problem of poorly-made hoverboards doesn’t stop in the United Kingdom: this past week a man in Alabama posted a video of his hoverboard on fire just three days after purchasing it, and this past Tuesday a house caught fire in Louisiana. The alleged cause: a hoverboard.

So shoppers, beware: If you’re going to buy a loved one a hoverboard, make sure it’s from a legitimate source. Otherwise the gift you may be giving your friends won’t make their Christmas, but rather ruin it.

(Image via Universal Pictures)