diff --git a/ChangeLog b/ChangeLog
index 4f39553386..6acde0d7ed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Oct 11 14:03:54 2010  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* error.c (syserr_initialize): set the encoding of Errno::*#message
+	  as locale. [ruby-dev:42358]
+
 Mon Oct 11 06:38:27 2010  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* ext/stringio/stringio.c (strio_set_encoding):
diff --git a/error.c b/error.c
index 479caff213..f05600f7fb 100644
--- a/error.c
+++ b/error.c
@@ -1057,6 +1057,7 @@ syserr_initialize(int argc, VALUE *argv, VALUE self)
     else {
 	mesg = rb_str_new2(err);
     }
+    rb_enc_associate(mesg, rb_locale_encoding());
     rb_call_super(1, &mesg);
     rb_iv_set(self, "errno", error);
     return self;
diff --git a/test/ruby/test_exception.rb b/test/ruby/test_exception.rb
index 18ecb404be..a26ade075b 100644
--- a/test/ruby/test_exception.rb
+++ b/test/ruby/test_exception.rb
@@ -312,4 +312,8 @@ end.join
     e = assert_raise(NoMethodError) {str.__send__(id)}
     assert_equal("undefined method `#{id}' for #{str.inspect}:String", e.message, bug3237)
   end
+
+  def test_errno
+    assert_equal(Encoding.find("locale"), Errno::EINVAL.new.message.encoding)
+  end
 end