diff --git a/ChangeLog b/ChangeLog
index a90498f695..ef2bfb6531 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+Mon Jan  7 21:40:36 2013  Shugo Maeda  <shugo@ruby-lang.org>
+
+	* vm_method.c (Init_eval_method): main.public and main.private
+	  should be private.
+
+	* proc.c (Init_Proc): main.define_method should be private.
+
+	* test/ruby/test_module.rb: related test.
+
 Mon Jan  7 20:48:47 2013  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* eval.c (Init_eval): main.include should be private.
diff --git a/proc.c b/proc.c
index c5122daed6..07592c12dd 100644
--- a/proc.c
+++ b/proc.c
@@ -2286,7 +2286,8 @@ Init_Proc(void)
     /* Kernel */
     rb_define_method(rb_mKernel, "define_singleton_method", rb_obj_define_method, -1);
 
-    rb_define_singleton_method(rb_vm_top_self(), "define_method", top_define_method, -1);
+    rb_define_private_method(rb_singleton_class(rb_vm_top_self()),
+			     "define_method", top_define_method, -1);
 }
 
 /*
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index 185c445091..340c37762a 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -1597,22 +1597,22 @@ class TestModule < Test::Unit::TestCase
     assert_raise(NameError){ m.instance_eval { remove_const(:__FOO__) } }
   end
 
-  def test_top_include_is_private
-    main = eval("self", TOPLEVEL_BINDING)
-    methods = main.singleton_class.private_instance_methods(false)
-    assert(methods.include?(:include))
+  def test_private_top_methods
+    assert_top_method_is_private(:include)
+    assert_top_method_is_private(:public)
+    assert_top_method_is_private(:private)
+    assert_top_method_is_private(:define_method)
+  end
 
-    assert_in_out_err([], <<-INPUT, ["true"], [])
-      module M
-      end
-      include M
-      p singleton_class < M
-    INPUT
+  private
 
-    assert_in_out_err([], <<-INPUT, [], /private method `include' called for main:Object \(NoMethodError\)/)
-      module M
-      end
-      self.include M
+  def assert_top_method_is_private(method)
+    top = eval("self", TOPLEVEL_BINDING)
+    methods = top.singleton_class.private_instance_methods(false)
+    assert(methods.include?(method), "#{method} should be private")
+
+    assert_in_out_err([], <<-INPUT, [], /private method `#{method}' called for main:Object \(NoMethodError\)/)
+      self.#{method}
     INPUT
   end
 end
diff --git a/vm_method.c b/vm_method.c
index f219d7cb43..cfeb012bde 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -1610,8 +1610,10 @@ Init_eval_method(void)
     rb_define_method(rb_cModule, "public_class_method", rb_mod_public_method, -1);
     rb_define_method(rb_cModule, "private_class_method", rb_mod_private_method, -1);
 
-    rb_define_singleton_method(rb_vm_top_self(), "public", top_public, -1);
-    rb_define_singleton_method(rb_vm_top_self(), "private", top_private, -1);
+    rb_define_private_method(rb_singleton_class(rb_vm_top_self()),
+			     "public", top_public, -1);
+    rb_define_private_method(rb_singleton_class(rb_vm_top_self()),
+			     "private", top_private, -1);
 
     object_id = rb_intern("object_id");
     added = rb_intern("method_added");