diff --git a/ChangeLog b/ChangeLog
index 3911555cb5..39bb972a57 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Thu Apr 18 16:58:51 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* vm_method.c (rb_mod_public_method): fix visibility on anonymous
+	  module. set visibility of singleton method, not method in base
+	  class.  [ruby-core:54404] [Bug #8284]
+
 Thu Apr 18 16:20:51 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* dir.c (glob_helper): should skip dot directories only for recursion,
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index 26fec5e899..9342a78617 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -1721,6 +1721,13 @@ class TestModule < Test::Unit::TestCase
     assert_equal [mod, obj.singleton_class, Object], obj.singleton_class.ancestors.first(3)
   end
 
+  def test_anonymous_module_public_class_method
+    bug8284 = '[ruby-core:54404] [Bug #8284]'
+    assert_raise(NoMethodError) {Object.define_method}
+    Module.new.public_class_method(:define_method)
+    assert_raise(NoMethodError, bug8284) {Object.define_method}
+  end
+
   private
 
   def assert_top_method_is_private(method)
diff --git a/vm_method.c b/vm_method.c
index b4c45180d6..badc20eb37 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -1374,7 +1374,7 @@ rb_mod_private(int argc, VALUE *argv, VALUE module)
 static VALUE
 rb_mod_public_method(int argc, VALUE *argv, VALUE obj)
 {
-    set_method_visibility(CLASS_OF(obj), argc, argv, NOEX_PUBLIC);
+    set_method_visibility(rb_singleton_class(obj), argc, argv, NOEX_PUBLIC);
     return obj;
 }
 
@@ -1400,7 +1400,7 @@ rb_mod_public_method(int argc, VALUE *argv, VALUE obj)
 static VALUE
 rb_mod_private_method(int argc, VALUE *argv, VALUE obj)
 {
-    set_method_visibility(CLASS_OF(obj), argc, argv, NOEX_PRIVATE);
+    set_method_visibility(rb_singleton_class(obj), argc, argv, NOEX_PRIVATE);
     return obj;
 }