diff --git a/ChangeLog b/ChangeLog
index ed7c82149d..44a9d83351 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+Wed Aug  1 05:50:53 2012  Hiroshi Shirosaki  <h.shirosaki@gmail.com>
+
+	* test/ruby/test_rubyoptions.rb (TestRubyOptions#test_encoding):
+	  Fix test_encoding failure on Windows.
+	  With chcp 65001, 1252 and 437, test_encoding failed. Test result
+	  depends on locale because LANG environment variable doesn't affect
+	  locale on Windows.
+	  [ruby-core:46872] [Bug #6813]
+
 Wed Aug  1 00:33:19 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* class.c (include_class_new): fix duplication of prepended module.
diff --git a/test/ruby/test_rubyoptions.rb b/test/ruby/test_rubyoptions.rb
index 1f2732cebb..87eb049baa 100644
--- a/test/ruby/test_rubyoptions.rb
+++ b/test/ruby/test_rubyoptions.rb
@@ -199,14 +199,21 @@ class TestRubyOptions < Test::Unit::TestCase
   end
 
   def test_encoding
-    assert_in_out_err(%w(-Eutf-8), "p '\u3042'", [], /invalid multibyte char/)
-
     assert_in_out_err(%w(--encoding), "", [], /missing argument for --encoding/)
 
     assert_in_out_err(%w(--encoding test_ruby_test_rubyoptions_foobarbazqux), "", [],
                       /unknown encoding name - test_ruby_test_rubyoptions_foobarbazqux \(RuntimeError\)/)
 
-    assert_in_out_err(%w(--encoding utf-8), "p '\u3042'", [], /invalid multibyte char/)
+    if /mswin|mingw/ =~ RUBY_PLATFORM &&
+      (str = "\u3042".force_encoding(Encoding.find("locale"))).valid_encoding?
+      # This result depends on locale because LANG=C doesn't affect locale
+      # on Windows.
+      out, err = [str], []
+    else
+      out, err = [], /invalid multibyte char/
+    end
+    assert_in_out_err(%w(-Eutf-8), "puts '\u3042'", out, err)
+    assert_in_out_err(%w(--encoding utf-8), "puts '\u3042'", out, err)
   end
 
   def test_syntax_check