diff --git a/ChangeLog b/ChangeLog
index e94f1143eb..b275ae201b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Sat Dec  1 18:16:49 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* id.c (Init_id), template/id.h.tmpl: add initialize_{copy,clone,dup}
+	  and respond_to_missing?.
+
+	* vm_method.c (rb_method_entry_make): make above methods private.
+	  [Feature #6539]
+
 Sat Dec  1 16:40:22 2012  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* test/ruby/test_thread.rb: move ConditionVariable related test
diff --git a/id.c b/id.c
index b6143971a1..0da29dffbe 100644
--- a/id.c
+++ b/id.c
@@ -26,6 +26,7 @@ Init_id(void)
     REGISTER_SYMID(idIFUNC, "<IFUNC>");
     REGISTER_SYMID(idCFUNC, "<CFUNC>");
     REGISTER_SYMID(idRespond_to, "respond_to?");
+    REGISTER_SYMID(idRespond_to_missing, "respond_to_missing?");
 
     REGISTER_SYMID(id_core_set_method_alias,   	    "core#set_method_alias");
     REGISTER_SYMID(id_core_set_variable_alias, 	    "core#set_variable_alias");
@@ -54,5 +55,8 @@ Init_id(void)
     REGISTER_SYMID(idSend, "send");
     REGISTER_SYMID(id__send__, "__send__");
     REGISTER_SYMID(idInitialize, "initialize");
+    REGISTER_SYMID(idInitialize_copy, "initialize_copy");
+    REGISTER_SYMID(idInitialize_clone, "initialize_clone");
+    REGISTER_SYMID(idInitialize_dup, "initialize_dup");
     REGISTER_SYMID(idUScore, "_");
 }
diff --git a/template/id.h.tmpl b/template/id.h.tmpl
index f7e764c123..d5e82a989e 100644
--- a/template/id.h.tmpl
+++ b/template/id.h.tmpl
@@ -28,6 +28,9 @@ method_ids = %w[
   Send
   __send__
   Initialize
+  Initialize_copy
+  Initialize_clone
+  Initialize_dup
   UScore
   Bitblt
   Answer
@@ -42,6 +45,7 @@ token_op_ids = %w[
 preserved_ids = %w[
   NULL
   Respond_to
+  Respond_to_missing
   IFUNC
   CFUNC
   _core_set_method_alias
diff --git a/test/ruby/test_method.rb b/test/ruby/test_method.rb
index a1572fde5e..06c1c2c08f 100644
--- a/test/ruby/test_method.rb
+++ b/test/ruby/test_method.rb
@@ -1,3 +1,4 @@
+# -*- coding: us-ascii -*-
 require 'test/unit'
 require_relative 'envutil'
 
@@ -31,6 +32,10 @@ class TestMethod < Test::Unit::TestCase
   end
   class T
     def initialize; end
+    def initialize_copy(*) super end
+    def initialize_clone(*) super end
+    def initialize_dup(*) super end
+    def respond_to_missing?(*) super end
     def normal_method; end
   end
   module M
@@ -329,6 +334,10 @@ class TestMethod < Test::Unit::TestCase
   def test_default_accessibility
     assert T.public_instance_methods.include?(:normal_method), 'normal methods are public by default'
     assert !T.public_instance_methods.include?(:initialize), '#initialize is private'
+    assert !T.public_instance_methods.include?(:initialize_copy), '#initialize_copy is private'
+    assert !T.public_instance_methods.include?(:initialize_clone), '#initialize_clone is private'
+    assert !T.public_instance_methods.include?(:initialize_dup), '#initialize_dup is private'
+    assert !T.public_instance_methods.include?(:respond_to_missing?), '#respond_to_missing? is private'
     assert !M.public_instance_methods.include?(:func), 'module methods are private by default'
     assert M.public_instance_methods.include?(:meth), 'normal methods are public by default'
   end
diff --git a/vm_method.c b/vm_method.c
index 6580bb6028..d5140f59d5 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -190,7 +190,9 @@ rb_method_entry_make(VALUE klass, ID mid, rb_method_type_t type,
     if (!FL_TEST(klass, FL_SINGLETON) &&
 	type != VM_METHOD_TYPE_NOTIMPLEMENTED &&
 	type != VM_METHOD_TYPE_ZSUPER &&
-	(mid == rb_intern("initialize") || mid == rb_intern("initialize_copy"))) {
+	(mid == idInitialize || mid == idInitialize_copy ||
+	 mid == idInitialize_clone || mid == idInitialize_dup ||
+	 mid == idRespond_to_missing)) {
 	noex = NOEX_PRIVATE | noex;
     }