diff --git a/Documentation/Doxyfile.in b/Documentation/Doxyfile.in
index 3dffbf82..86bcc4d0 100644
--- a/Documentation/Doxyfile.in
+++ b/Documentation/Doxyfile.in
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: CC-BY-SA-4.0
 # Doxyfile 1.8.14
 
 # This file describes the settings to be used by the documentation system