diff --git a/include/libopencm3/usb/usbstd.h b/include/libopencm3/usb/usbstd.h
index 8610fdbc..5b1cea4d 100644
--- a/include/libopencm3/usb/usbstd.h
+++ b/include/libopencm3/usb/usbstd.h
@@ -38,6 +38,9 @@ struct usb_setup_data {
 	u16 wLength;
 } __attribute__((packed));
 
+/* Class Definition */
+#define USB_CLASS_VENDOR            		0xFF
+
 /* bmRequestType bit definitions */
 #define USB_REQ_TYPE_IN				0x80
 #define USB_REQ_TYPE_STANDARD			0x00