Earlier this month, a pair of security researchers used a wireless attack to disable a Jeep Cherokee as I drove it on a Missouri highway. Though it was just a demonstration, I learned that trying to drive a vehicle as it’s paralyzed by faraway hackers isn’t pleasant. Luckily for Jeep owners, there’s still time to avoid sharing that experience.

Last week, Chrysler quietly released a software update for a collection of its vehicles that have an internet-connected computer feature in their dashboard known as Uconnect. The carmaker posted a notice to its website informing its customers about a “software update to improve vehicle electronic security.” What it didn’t explain in that cryptic post is that the update includes a patch designed to prevent the attack developed by security researchers Charlie Miller and Chris Valasek, which can compromise those Uconnect computers—an optional upgrade feature that doesn’t come standard in the Chrysler vehicles—through their cellular Internet connection to tamper with dashboard functions and track their GPS coordinates. For 2014 Jeep Cherokees in particular, Miller and Valasek have extended their attack to the vehicle’s CAN bus, the network that controls functions like steering, brakes, and transmission. That’s how they were able to wirelessly disconnect the Jeep’s engine with me behind the wheel, and later disable the brakes to send me rolling into a ditch.

At the Black Hat security conference next month, they plan to publish a portion of that exploit to allow for peer review of their work. They’re also sending a message: “Cars should be secure,” says Miller. “If consumers don’t realize this is an issue, they should, and they should start complaining to carmakers.”

They should also learn to patch their car’s vulnerable software. Miller and Valasek have been working with Chrysler for the last nine months to help the company create the patch it discreetly revealed last week. If you have a late-model Chrysler with that Uconnect feature, you should manually update its software now.

Here’s how: Visit this link, enter your vehicle identification number (here’s a guide to finding it), and download the update. Move the update onto a USB drive, and plug it into your Chrysler vehicle’s dashboard USB port. The Uconnect system will ask if you want to update its software, and confirm that you do. You can also take your Chrysler to your dealership, whose mechanics will update its software for free.

In a statement to WIRED, Chrysler listed several 2013-2014 models of Dodge Ram, the 2013-2014 Dodge Viper, the 2014 Jeep Cherokee, Jeep Grand Cherokee, and Dodge Durango as all vulnerable to the Uconnect attack. But Miller and Valasek say they’ve scanned Uconnect’s Sprint-enabled network and found other hackable vehicles, including 2015 Jeep Cherokees, 2015 Jeep Grand Cherokees, and 2015 Chrysler 200s. Owners of those latter vehicles should update, too. With repeated scans of the Uconnect network and an algorithm sometimes used for tracking and counting wildlife, Miller and Valasek estimate that there are as many as 471,000 vulnerable Chrysler vehicles on the road.

Miller says he’s briefly tested the patch, and it appears to fix the flaw he and Valasek used. “It seems like our attacks don’t work anymore,” he says, a little uncertainly. “I wouldn’t stake my life on it.”

If you’re one of those hundreds of thousands of Chrysler drivers with potentially insecure cars, the patch may be the best option you’ve got.

Read WIRED’s full story on Miller and Valasek’s car hacking research here.