--- a/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/ir/LexicalContext.java	Tue Sep 10 15:30:23 2019 +0200
+++ b/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/ir/LexicalContext.java	Tue Sep 10 15:35:35 2019 +0200
@@ -697,7 +697,7 @@
      * @return {@code true} if in unprotected switch statement.
      */
     public boolean inUnprotectedSwitchContext() {
-        for (int i = sp; i > 0; i--) {
+        for (int i = sp - 1; i > 0; i--) {
             final LexicalContextNode next = stack[i];
             if (next instanceof Block) {
                 return stack[i - 1] instanceof SwitchNode;

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/nashorn/script/basic/es6/JDK-8230709.js	Tue Sep 10 15:35:35 2019 +0200
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * JDK-8230709: Array index out of bounds in ES6 mode
+ *
+ * @test
+ * @run
+ * @option --language=es6
+ */
+
+{{{{{{{{{{{{{{{ let x; }}}}}}}}}}}}}}}