diff --git a/crates/cpu/src/next_pc/next_pc.mermaid b/crates/cpu/src/next_pc/next_pc.mermaid
index 613e4b3..87deefb 100644
--- a/crates/cpu/src/next_pc/next_pc.mermaid
+++ b/crates/cpu/src/next_pc/next_pc.mermaid
@@ -1,3 +1,5 @@
+%% SPDX-License-Identifier: LGPL-3.0-or-later
+%% See Notices.txt for copyright information
 stateDiagram-v2
     direction LR
 
diff --git a/scripts/check-copyright.sh b/scripts/check-copyright.sh
index 43d3b08..8a00081 100755
--- a/scripts/check-copyright.sh
+++ b/scripts/check-copyright.sh
@@ -31,6 +31,7 @@ function check_file()
 POUND_HEADER=('^"# SPDX-License-Identifier: LGPL-3.0-or-later"$' '^"# See Notices.txt for copyright information"$')
 SLASH_HEADER=('^"// SPDX-License-Identifier: LGPL-3.0-or-later"$' '^"// See Notices.txt for copyright information"$')
 MD_HEADER=('^"<!--"$' '^"SPDX-License-Identifier: LGPL-3.0-or-later"$' '^"See Notices.txt for copyright information"$')
+MERMAID_HEADER=('^"%% SPDX-License-Identifier: LGPL-3.0-or-later"$' '^"%% See Notices.txt for copyright information"$')
 
 function main()
 {
@@ -51,6 +52,9 @@ function main()
         /.forgejo/workflows/*.yml|*/.gitignore|*.toml)
             check_file "$file" "${POUND_HEADER[@]}"
             ;;
+        *.mermaid)
+            check_file "$file" "${MERMAID_HEADER[@]}"
+            ;;
         *.md)
             check_file "$file" "${MD_HEADER[@]}"
             ;;