More and more Internet of Things (IoT) devices are deployed around the world, due to the convenience and extra functionality they enable. This growth, while great for the industry as a whole, has come at a price with respect to ensuring and maintaining security and privacy. Having that in mind, one of the most common solutions to the IoT security problem is to update the devices frequently. Recently, LoRa Alliance has released a new specification (FUOTA) on how to perform firmware updates using LoRa technology. In this paper, we propose a blockchain-based framework to securely update the firmware of the IoT devices using the LoRa communication protocol. As a first step, we perform an evaluation of the firmware update procedure using different network sizes and different firmware sizes. The evaluation shows that there is a need to use more gateways that will collaborate to increase the reliability and the performance of the firmware update process.