diff --git a/docs/sharpemu-gui-undocumented-env-vars.md b/docs/sharpemu-gui-undocumented-env-vars.md
index cce83bc..771eb8d 100644
--- a/docs/sharpemu-gui-undocumented-env-vars.md
+++ b/docs/sharpemu-gui-undocumented-env-vars.md
@@ -1,3 +1,8 @@
+<!--
+Copyright (C) 2026 SharpEmu Emulator Project
+SPDX-License-Identifier: GPL-2.0-or-later
+-->
+
 # SharpEmu: environment variables that are not on the GUI options pages
 
 ## Scope