diff --git a/SC2221.md b/SC2221.md
index ad33e26..40781b1 100644
--- a/SC2221.md
+++ b/SC2221.md
@@ -15,6 +15,7 @@ esac
 ```sh
 case "$1" in
   -\?) echo "Usage: $0 [-n]";;
+# '-?') echo "Usage: $0 [-n]";;  # Also valid
   -n) echo "Hello World";;
    *) exit 1;;
 esac