--- a/jdk/src/java.base/share/classes/java/lang/invoke/LambdaFormEditor.java	Fri Feb 27 11:45:07 2015 +0000
+++ b/jdk/src/java.base/share/classes/java/lang/invoke/LambdaFormEditor.java	Fri Feb 27 18:03:21 2015 +0300
@@ -436,7 +436,7 @@
     }
 
     private MethodType bindArgumentType(BoundMethodHandle mh, int pos, BasicType bt) {
-        assert(mh.form == lambdaForm);
+        assert(mh.form.uncustomize() == lambdaForm);
         assert(mh.form.names[1+pos].type == bt);
         assert(BasicType.basicType(mh.type().parameterType(pos)) == bt);
         return mh.type().dropParameterTypes(pos, pos+1);

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/lang/invoke/CustomizedLambdaFormTest.java	Fri Feb 27 18:03:21 2015 +0300
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2015, 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.
+ */
+
+package java.lang.invoke;
+
+/* @test
+ * @summary Assertion in LambdaFormEditor.bindArgumentType is too strong
+ *
+ * @run main/bootclasspath -esa java.lang.invoke.CustomizedLambdaFormTest
+ */
+public class CustomizedLambdaFormTest {
+
+    static void testExtendCustomizedBMH() throws Exception {
+        // Construct BMH
+        MethodHandle mh = MethodHandles.Lookup.IMPL_LOOKUP.findVirtual(String.class, "concat",
+                MethodType.methodType(String.class, String.class))
+                .bindTo("a");
+        mh.customize();
+        mh.bindTo("b"); // Try to extend customized BMH
+    }
+
+    public static void main(String[] args) throws Throwable {
+        testExtendCustomizedBMH();
+    }
+}