diff --git a/ChangeLog b/ChangeLog
index 678678b3f9..a90498f695 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Mon Jan  7 20:48:47 2013  Shugo Maeda  <shugo@ruby-lang.org>
+
+	* eval.c (Init_eval): main.include should be private.
+	  [ruby-core:51293] [Bug #7670]
+
+	* test/ruby/test_module.rb (test_top_include_is_private): a new test
+	  for the above change.
+
 Mon Jan  7 20:29:50 2013  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* NEWS: remove description about `require "refinement"'.
diff --git a/eval.c b/eval.c
index ea78edc66a..2c24474d3f 100644
--- a/eval.c
+++ b/eval.c
@@ -1551,7 +1551,8 @@ Init_eval(void)
     rb_define_singleton_method(rb_cModule, "nesting", rb_mod_nesting, 0);
     rb_define_singleton_method(rb_cModule, "constants", rb_mod_s_constants, -1);
 
-    rb_define_singleton_method(rb_vm_top_self(), "include", top_include, -1);
+    rb_define_private_method(rb_singleton_class(rb_vm_top_self()),
+			     "include", top_include, -1);
     rb_define_private_method(rb_singleton_class(rb_vm_top_self()),
 			     "using", top_using, 1);
 
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index 2862cd338f..185c445091 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -1596,4 +1596,23 @@ class TestModule < Test::Unit::TestCase
     m = Module.new
     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))
+
+    assert_in_out_err([], <<-INPUT, ["true"], [])
+      module M
+      end
+      include M
+      p singleton_class < M
+    INPUT
+
+    assert_in_out_err([], <<-INPUT, [], /private method `include' called for main:Object \(NoMethodError\)/)
+      module M
+      end
+      self.include M
+    INPUT
+  end
 end