--- a/nashorn/src/jdk/nashorn/internal/runtime/ScriptObject.java	Thu Jan 24 12:15:29 2013 -0400
+++ b/nashorn/src/jdk/nashorn/internal/runtime/ScriptObject.java	Thu Jan 24 22:38:58 2013 +0530
@@ -2076,7 +2076,7 @@
         final int parameterCount = methodType.parameterCount();
         final int callCount      = callType.parameterCount();
 
-        final boolean isCalleeVarArg = parameterCount > 1 && methodType.parameterType(parameterCount - 1).isArray();
+        final boolean isCalleeVarArg = parameterCount > 0 && methodType.parameterType(parameterCount - 1).isArray();
         final boolean isCallerVarArg = callerVarArg != null ? callerVarArg.booleanValue() : (callCount > 1 &&
                 callType.parameterType(callCount - 1).isArray());
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/test/script/basic/JDK-8006857.js	Thu Jan 24 22:38:58 2013 +0530
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2010, 2013, 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-8006857: ClassCastException when interface implementing function uses arguments object
+ *
+ * @test
+ * @run
+ */
+
+
+function run() {
+    print(arguments);
+    print("in run");
+}
+
+var t = new java.lang.Thread(run);
+t.start();
+t.join();
+
+var r = new java.lang.Runnable() {
+        run: function() {
+            print(arguments);
+            print("in run");
+        }
+    };
+
+r.run();

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/test/script/basic/JDK-8006857.js.EXPECTED	Thu Jan 24 22:38:58 2013 +0530
@@ -0,0 +1,4 @@
+[object Arguments]
+in run
+[object Arguments]
+in run