+#ifndef SERIAL_NUMBER
+ #define SERIAL_NUMBER 0
+#endif
+
+const USB_Descriptor_String_t PROGMEM SerialNumberString =
+{
+ /* subtract 1 for null terminator */
+ .Header = {.Size = USB_STRING_LEN(sizeof(STR(SERIAL_NUMBER))-1), .Type = DTYPE_String},
+
+ .UnicodeString = LSTR(SERIAL_NUMBER)
+};
+