--- a/jdk/src/share/classes/java/lang/invoke/InnerClassLambdaMetafactory.java	Wed Oct 23 14:32:41 2013 -0700
+++ b/jdk/src/share/classes/java/lang/invoke/InnerClassLambdaMetafactory.java	Wed Oct 23 15:16:35 2013 -0700
@@ -33,8 +33,10 @@
 import java.lang.reflect.Constructor;
 import java.security.AccessController;
 import java.security.PrivilegedAction;
+import java.util.LinkedHashSet;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.PropertyPermission;
+import java.util.Set;
 
 import static jdk.internal.org.objectweb.asm.Opcodes.*;
 
@@ -226,11 +228,20 @@
      * is not found
      */
     private Class<?> spinInnerClass() throws LambdaConversionException {
-        String[] interfaces = new String[markerInterfaces.length + 1];
-        interfaces[0] = samBase.getName().replace('.', '/');
-        for (int i=0; i<markerInterfaces.length; i++) {
-            interfaces[i+1] = markerInterfaces[i].getName().replace('.', '/');
+        String[] interfaces;
+        String samIntf = samBase.getName().replace('.', '/');
+        if (markerInterfaces.length == 0) {
+            interfaces = new String[]{samIntf};
+        } else {
+            // Assure no duplicate interfaces (ClassFormatError)
+            Set<String> itfs = new LinkedHashSet<>(markerInterfaces.length + 1);
+            itfs.add(samIntf);
+            for (int i = 0; i < markerInterfaces.length; i++) {
+                itfs.add(markerInterfaces[i].getName().replace('.', '/'));
+            }
+            interfaces = itfs.toArray(new String[itfs.size()]);
         }
+
         cw.visit(CLASSFILE_VERSION, ACC_SUPER + ACC_FINAL + ACC_SYNTHETIC,
                  lambdaClassName, null,
                  JAVA_LANG_OBJECT, interfaces);

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/lang/invoke/lambda/DupIntf.java	Wed Oct 23 15:16:35 2013 -0700
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 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.
+ */
+
+/*
+ * @test
+ * @bug 8025868
+ * @summary Lambda class can be generated with duplicate interfaces (ClassFormatError)
+ * @run main DupIntf
+ */
+
+interface SAM<P1> {
+    P1 m();
+}
+
+interface Other { }
+
+public class DupIntf {
+    public static void main(String argv[]) {
+        SAM<?> sam = (SAM<?> & Other) () -> "Pass.";
+        System.out.println(sam.m());
+    }
+}