diff --git a/ports/zephyr-cp/supervisor/usb.c b/ports/zephyr-cp/supervisor/usb.c
index da22cbb0d35..a926bc1554e 100644
--- a/ports/zephyr-cp/supervisor/usb.c
+++ b/ports/zephyr-cp/supervisor/usb.c
@@ -49,6 +49,10 @@ USBD_DEVICE_DEFINE(main_usbd,
 USBD_DESC_LANG_DEFINE(main_lang);
 USBD_DESC_MANUFACTURER_DEFINE(main_mfr, USB_MANUFACTURER);
 USBD_DESC_PRODUCT_DEFINE(main_product, USB_PRODUCT);
+// The stack fills this from hwinfo and fails the request without a driver.
+#if defined(CONFIG_HWINFO_HAS_DRIVER)
+USBD_DESC_SERIAL_NUMBER_DEFINE(main_sn);
+#endif
 
 USBD_DESC_CONFIG_DEFINE(fs_cfg_desc, "FS Configuration");
 USBD_DESC_CONFIG_DEFINE(hs_cfg_desc, "HS Configuration");
@@ -268,6 +272,14 @@ void usb_init(void) {
         return;
     }
 
+    #if defined(CONFIG_HWINFO_HAS_DRIVER)
+    err = usbd_add_descriptor(&main_usbd, &main_sn);
+    if (err) {
+        LOG_ERR("Failed to initialize serial number descriptor (%d)", err);
+        return;
+    }
+    #endif
+
     bool console = usb_cdc_console_enabled();
     if (console) {
         uint8_t *receiver_buffer = port_malloc(128, true);