diff --git a/include/libopencm3/usb/usbd.h b/include/libopencm3/usb/usbd.h
index b4f6bcdb..b50c65d2 100644
--- a/include/libopencm3/usb/usbd.h
+++ b/include/libopencm3/usb/usbd.h
@@ -86,7 +86,7 @@ extern int usbd_register_control_callback(usbd_device *usbd_dev, uint8_t type,
 					  usbd_control_callback callback);
 
 /* <usb_standard.c> */
-extern void usbd_register_set_config_callback(usbd_device *usbd_dev,
+extern int usbd_register_set_config_callback(usbd_device *usbd_dev,
 	void (*callback)(usbd_device *usbd_dev, uint16_t wValue));
 
 /* Functions to be provided by the hardware abstraction layer */