diff --git a/cipherscan b/cipherscan
index feac6b1..6107a33 100755
--- a/cipherscan
+++ b/cipherscan
@@ -1991,11 +1991,11 @@ do
             shift
             break
             ;;
-        # -*)
-        #     UNKNOWNOPTIONS=$((UNKNOWNOPTIONS+$1))
-        #     # echo "WARN: Unknown option (ignored): $1" >&2
-        #     shift
-        #     ;;
+        -*)
+            UNKNOWNOPTIONS=$((UNKNOWNOPTIONS+$1))
+            echo "$0: Unknown option: $1" >&2
+            exit 1
+            ;;
         *)  # no more options we understand.
             break
             ;;