Your phone deserves a noble retirement. After all, it’s served you faithfully and proven its worth for so long, waking you up on time, reminding you of upcoming events, and helping you stay in touch with your friends and family. So when you’re ready to trade up for a newer model, don’t just throw your old phone away. Instead, download one last app, and turn your it into a smart smoke alarm.

Bringing the concept of “reduce, reuse, and recycle” to modern technology, smart home security company Cleverloop has developed an app called Smokey, available for both iPhone and Android. While you should be able to hear an alarm when you’re at home yourself, sometimes the unexpected happens when you’re away from the premises. And in these situations, having Smokey could be critical.

By using the built-in microphone on a used smartphone or tablet, the Smokey app helps you monitor your home for smoke in real time even when you’re on the go. If it hears a smoke alarm go off, it’ll send you an SMS and warn you of potential danger. And while other smart smoke alarm systems may necessitate multiple devices and cost hundreds of dollars, Smokey is completely free, and simply makes use of a mobile device you’re no longer using.

“Being in the smart home security business, we are always thinking about ways to make our customers more secure and to give them peace of mind,” said CleverLoop CMO Richard Smith. “We found the most efficient and cost effective solution for smart smoke detection was to enable users to reuse their old devices with a simple, free app.”

To set up the app, simply download Smokey onto your old device, and then place the tablet or smartphone in a central part of your home, where it’s sure to pick up an alarm sound. Then, plug in the device and connect it to your WiFi network. Once you’ve entered your phone number or email in the Smokey app for notifications, arm the system, and rest assured that your smart detection system is up and running.

“We are very excited to be able to provide our customers and the public a better way to keep their homes and family safe,” added Smith. So put that old smartphone to new use, and help keep yourself and your loved ones safe.