Random number generation is crucial for secure communications and simulations. While classical generators have inherent limitations due to determinism, quantum random number generators offer a safer alternative. However, most generators depend on assumptions about their hardware, posing a risk if compromised. This paper presents a semi-device-independent protocol, reducing reliance on the generators’ components. The scheme is based on the prepare-and-measure scenario and operates under an easy-to-verify assumption related to the laser’s mean-photon number, employing a CMOS sensor as the practical detector. Using a correlation test of preparation and measurement, we validate the generated randomness even with untrusted devices.