In August 2025, Oyvind Hagen addressed a critical issue in the Zephyr repository by fixing the USB CDC ACM serial state notification, ensuring accurate reporting of the Rx Carrier status. Working primarily in C and leveraging expertise in device drivers and embedded systems, Oyvind modified the driver to send the actual serial state value rather than a static flag. This technical approach improved the reliability of USB device behavior in production environments by reducing erroneous carrier state signals. The work demonstrated a focused, in-depth contribution to the zephyrproject-rtos/zephyr codebase, enhancing both device reliability and the accuracy of serial state notifications.