diff --git a/ChangeLog b/ChangeLog
index 1964d66472..fb39f0a05e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Tue Sep 27 03:32:27 2011  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
+
+	* test/psych/test_yamldbm.rb (require): fix #setup and #terdown.
+	  [Bug #5370] [ruby-core:39730]
+	* test/syck/test_yamldbm.rb (require): ditto.
+
 Mon Sep 26 11:27:38 2011  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* lib/webrick/httputils.rb: Add MIME Type definition of .js and .svg.
diff --git a/test/psych/test_yamldbm.rb b/test/psych/test_yamldbm.rb
index f1e4425686..6dfe23c57f 100644
--- a/test/psych/test_yamldbm.rb
+++ b/test/psych/test_yamldbm.rb
@@ -1,19 +1,28 @@
 # -*- coding: UTF-8 -*-
 require 'test/unit'
 require 'yaml/dbm'
+require 'tmpdir'
 Psych::DBM = YAML::DBM unless defined?(Psych::DBM)
 
 module Psych
   class YAMLDBMTest < Test::Unit::TestCase
     def setup
       @engine, YAML::ENGINE.yamler = YAML::ENGINE.yamler, 'psych'
-      @yamldbm_file = "yamldbm.tmp.#{Process.pid}"
+      @dir = Dir.mktmpdir("rubytest-file")
+      File.chown(-1, Process.gid, @dir)
+      @yamldbm_file = make_tmp_filename("yamldbm")
       @yamldbm = YAML::DBM.new(@yamldbm_file)
     end
 
     def teardown
       YAML::ENGINE.yamler = @engine
-      File.unlink(@yamldbm_file + '.db') rescue nil
+      @yamldbm.clear
+      @yamldbm.close
+      FileUtils.remove_entry_secure @dir
+    end
+
+    def make_tmp_filename(prefix)
+      @dir + "/" + prefix + File.basename(__FILE__) + ".#{$$}.test"
     end
 
     def test_store
diff --git a/test/syck/test_yamldbm.rb b/test/syck/test_yamldbm.rb
index 12b3b18eca..01a2df678b 100644
--- a/test/syck/test_yamldbm.rb
+++ b/test/syck/test_yamldbm.rb
@@ -1,19 +1,28 @@
 # -*- coding: UTF-8 -*-
 require 'test/unit'
 require 'yaml/dbm'
+require 'tmpdir'
 Syck::DBM = YAML::DBM unless defined?(Syck::DBM)
 
 module Syck
   class YAMLDBMTest < Test::Unit::TestCase
     def setup
-      @engine, YAML::ENGINE.yamler = YAML::ENGINE.yamler, 'syck'
-      @yamldbm_file = "yamldbm.tmp.#{Process.pid}"
+      @engine, YAML::ENGINE.yamler = YAML::ENGINE.yamler, 'psych'
+      @dir = Dir.mktmpdir("rubytest-file")
+      File.chown(-1, Process.gid, @dir)
+      @yamldbm_file = make_tmp_filename("yamldbm")
       @yamldbm = YAML::DBM.new(@yamldbm_file)
     end
 
     def teardown
       YAML::ENGINE.yamler = @engine
-      File.unlink(@yamldbm_file + '.db') rescue nil
+      @yamldbm.clear
+      @yamldbm.close
+      FileUtils.remove_entry_secure @dir
+    end
+
+    def make_tmp_filename(prefix)
+      @dir + "/" + prefix + File.basename(__FILE__) + ".#{$$}.test"
     end
 
     def test_store