diff --git a/.github/workflows/scripts/check-license-header.sh b/.github/workflows/scripts/check-license-header.sh
index 10cc4ed..41b3d4d 100755
--- a/.github/workflows/scripts/check-license-header.sh
+++ b/.github/workflows/scripts/check-license-header.sh
@@ -67,6 +67,7 @@ while IFS= read -r file_path; do
     json) continue ;; # JSON doesn't support comments
     jsx) expected_file_header=$(sed -e 's|@@|//|g' <<<"${expected_file_header_template}") ;;
     kts) expected_file_header=$(sed -e 's|@@|//|g' <<<"${expected_file_header_template}") ;;
+    proto) expected_file_header=$(sed -e 's|@@|//|g' <<<"${expected_file_header_template}") ;;
     ps1) expected_file_header=$(sed -e 's|@@|##|g' <<<"${expected_file_header_template}") ;;
     py) expected_file_header=$(cat <(echo '#!/usr/bin/env python3') <(sed -e 's|@@|##|g' <<<"${expected_file_header_template}")) ;;
     rb) expected_file_header=$(cat <(echo '#!/usr/bin/env ruby') <(sed -e 's|@@|##|g' <<<"${expected_file_header_template}")) ;;