diff --git a/scripts/scylla-jmx b/scripts/scylla-jmx
index 9e7a863..447bef6 100755
--- a/scripts/scylla-jmx
+++ b/scripts/scylla-jmx
@@ -82,6 +82,9 @@ do
       shift 1
       ;;
     *)
+      echo "Unknown parameter: $1"
+      print_help
+      exit 1
     esac
 done