diff --git a/include/usb.h b/include/usb.h
index bcad552..efb67ea 100644
--- a/include/usb.h
+++ b/include/usb.h
@@ -242,6 +242,12 @@
 
 #ifdef CONFIG_USB_KEYBOARD
 
+/*
+ * USB Keyboard reports are 8 bytes in boot protocol.
+ * Appendix B of HID Device Class Definition 1.11
+ */
+#define USB_KBD_BOOT_REPORT_SIZE 8
+
 int drv_usb_kbd_init(void);
 int usb_kbd_deregister(int force);