diff --git a/components/tinyusb_dfu/additions/src/tinyusb.c b/components/tinyusb_dfu/additions/src/tinyusb.c
index 9c2081c..0bf7003 100644
--- a/components/tinyusb_dfu/additions/src/tinyusb.c
+++ b/components/tinyusb_dfu/additions/src/tinyusb.c
@@ -54,6 +54,14 @@ esp_err_t tinyusb_driver_install(const tinyusb_config_t *config)
     ESP_RETURN_ON_ERROR(usb_new_phy(&phy_conf, &phy_hdl), TAG, "Install USB PHY failed");
 
     dev_descriptor = config->descriptor ? config->descriptor : &descriptor_kconfig;
+    if (!config->string_descriptor) { // use configured strings
+        // set MAC as serial
+        uint8_t mac[6];
+        esp_read_mac(mac, ESP_MAC_ETH);
+        static char usb_serial[13] = {0};
+        snprintf(usb_serial, sizeof(usb_serial), "%02X%02X%02X%02X%02X%02X", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+        descriptor_str_kconfig[3] = usb_serial;
+    }
     string_descriptor = config->string_descriptor ? config->string_descriptor : descriptor_str_kconfig;
 
     tusb_set_descriptor(dev_descriptor, string_descriptor);