diff --git a/ChangeLog b/ChangeLog
index f4fcc66d4d..a78c763994 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+Tue Jun 18 02:49:20 2013  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* test/ruby/envutil.rb (assert_separately): stop_auto_run of
+	  Test::Unit::Runner to prevent auto runner use ARGV.
+
+	* test/ruby/envutil.rb (assert_separately): add $: to separate process.
+
+	* test/ruby/envutil.rb (assert_separately): fail if stderr is not
+	  empty and ignore_stderr is false.
+
 Tue Jun 18 02:21:54 2013  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* test/ruby/envutil.rb (EnvUtil.with_default_external): add for
diff --git a/test/ruby/envutil.rb b/test/ruby/envutil.rb
index 0aa97e4341..cceadb9495 100644
--- a/test/ruby/envutil.rb
+++ b/test/ruby/envutil.rb
@@ -286,17 +286,31 @@ module Test
   ensure
     puts [Marshal.dump($!)].pack('m'), "assertions=\#{self._assertions}"
   end
+  class Test::Unit::Runner
+    @@stop_auto_run = true
+  end
 eom
+        args = args.dup
+        $:.each{|l| args.unshift "-I#{l}" }
+        ignore_stderr = opt.delete(:ignore_stderr)
         stdout, stderr, status = EnvUtil.invoke_ruby(args, src, true, true, opt)
         abort = status.coredump? || (status.signaled? && ABORT_SIGNALS.include?(status.termsig))
         assert(!abort, FailDesc[status, stderr])
         self._assertions += stdout[/^assertions=(\d+)/, 1].to_i
         res = Marshal.load(stdout.unpack("m")[0])
-        return unless res
-        res.backtrace.each do |l|
-          l.sub!(/\A-:(\d+)/){"#{file}:#{line + $1.to_i}"}
+        if res
+          res.backtrace.each do |l|
+            l.sub!(/\A-:(\d+)/){"#{file}:#{line + $1.to_i}"}
+          end
+          raise res
         end
-        raise res
+
+        # really is it succeed?
+        unless ignore_stderr
+          # the body of assert_separately must not output anything to detect errror
+          assert_equal("", stderr, "assert_separately failed with error message")
+        end
+        assert_equal(0, status, "assert_separately failed: '#{stderr}'")
       end
 
       def assert_warning(pat, message = nil)
diff --git a/test/ruby/test_require.rb b/test/ruby/test_require.rb
index ff5a519638..c03876d223 100644
--- a/test/ruby/test_require.rb
+++ b/test/ruby/test_require.rb
@@ -423,7 +423,7 @@ class TestRequire < Test::Unit::TestCase
     # in C-level.  And redirecting stderr to a pipe seems to change
     # some blocking timings and causes a deadlock, so run in a
     # separated process for the time being.
-    assert_separately(["-w", "-", path, bug5754], <<-'end;')
+    assert_separately(["-w", "-", path, bug5754], <<-'end;', ignore_stderr: true)
     path, bug5754 = *ARGV
     start = false
 
diff --git a/version.h b/version.h
index 632351734b..b11950e4d2 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.0.0"
 #define RUBY_RELEASE_DATE "2013-06-18"
-#define RUBY_PATCHLEVEL 225
+#define RUBY_PATCHLEVEL 226
 
 #define RUBY_RELEASE_YEAR 2013
 #define RUBY_RELEASE_MONTH 6