diff --git a/xen/include/public/errno.h b/xen/include/public/errno.h
index 5c53af6af9..6bdc8c5079 100644
--- a/xen/include/public/errno.h
+++ b/xen/include/public/errno.h
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: MIT */
+
 /*
  * There are two expected ways of including this header.
  *