diff --git a/ChangeLog b/ChangeLog
index 4eb5e2eb31..f09518718b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Thu Sep 18 16:26:27 2014  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* test/rubygems/test_gem_commands_setup_command.rb: @ui uses StringIO
+	  as its streams, and Encoding.default_external does not effect to
+	  stringIOs already exist.  so, we need to set external_encoding of
+	  @ui.outs directly.  this problem (test failure) does not appear in
+	  the environments default_external is us-ascii or utf-8.
+
 Thu Sep 18 15:02:15 2014  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* test/rubygems/test_gem_specification.rb: '/' is not always the root.
diff --git a/test/rubygems/test_gem_commands_setup_command.rb b/test/rubygems/test_gem_commands_setup_command.rb
index 2fe3384954..974c157a18 100644
--- a/test/rubygems/test_gem_commands_setup_command.rb
+++ b/test/rubygems/test_gem_commands_setup_command.rb
@@ -77,10 +77,10 @@ class TestGemCommandsSetupCommand < Gem::TestCase
 
   def test_show_release_notes
     @default_external = nil
-    capture_io do
-      @default_external, Encoding.default_external =
-        Encoding.default_external, Encoding::US_ASCII
-    end if Object.const_defined? :Encoding
+    if Object.const_defined? :Encoding
+      @default_external = @ui.outs.external_encoding
+      @ui.outs.set_encoding Encoding::US_ASCII
+    end
 
     @cmd.options[:previous_version] = Gem::Version.new '2.0.2'
 
@@ -127,11 +127,9 @@ class TestGemCommandsSetupCommand < Gem::TestCase
     output = @ui.output
     output.force_encoding Encoding::UTF_8 if Object.const_defined? :Encoding
 
-    assert_equal expected, @ui.output
+    assert_equal expected, output
   ensure
-    capture_io do
-      Encoding.default_external = @default_external
-    end if @default_external
+    @ui.outs.set_encoding @default_external if @default_external
   end
 
 end