diff --git a/core/resources/l10n/rename.sh b/core/resources/l10n/rename.sh
index c21c1f645..96ca24600 100755
--- a/core/resources/l10n/rename.sh
+++ b/core/resources/l10n/rename.sh
@@ -2,6 +2,9 @@
 
 # Usage:
 # ./rename <file-containing-rename-keys> <files_to_modify ...>
+#
+# Rename keys file contains space-separated lines:
+#    <old.key> <new.key>
 
 RENAME="$1"
 shift