diff --git a/ChangeLog b/ChangeLog
index 5a0d061ea9..2a850ae90d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Sun Oct  9 11:06:52 2011  Kazuki Tsujimoto  <kazuki@callcc.net>
+
+	* test/psych/test_yamldbm.rb: don't run test if the system
+	  don't support yaml/dbm.
+
+	* test/syck/test_yamldbm.rb: ditto.
+
 Sat Oct  8 08:54:56 2011  Eric Hodel  <drbrain@segment7.net>
 
 	* enum.c (group_by):  Improve group_by description.  Patch by b t.
diff --git a/test/psych/test_yamldbm.rb b/test/psych/test_yamldbm.rb
index 165125f65e..c60a18febe 100644
--- a/test/psych/test_yamldbm.rb
+++ b/test/psych/test_yamldbm.rb
@@ -1,10 +1,14 @@
 # -*- coding: UTF-8 -*-
-require 'test/unit'
-require 'yaml/dbm'
-require 'tmpdir'
-Psych::DBM = YAML::DBM unless defined?(Psych::DBM)
+begin
+  require 'test/unit'
+  require 'yaml/dbm'
+  require 'tmpdir'
+rescue LoadError
+end
 
 module Psych
+  ::Psych::DBM = ::YAML::DBM unless defined?(::Psych::DBM)
+
   class YAMLDBMTest < Test::Unit::TestCase
     def setup
       @engine, YAML::ENGINE.yamler = YAML::ENGINE.yamler, 'psych'
@@ -187,4 +191,4 @@ module Psych
       assert_equal([], @yamldbm.select {false})
     end
   end
-end
+end if defined?(YAML::DBM)
diff --git a/test/syck/test_yamldbm.rb b/test/syck/test_yamldbm.rb
index f017dd090d..a4a3afb66a 100644
--- a/test/syck/test_yamldbm.rb
+++ b/test/syck/test_yamldbm.rb
@@ -1,10 +1,14 @@
 # -*- coding: UTF-8 -*-
-require 'test/unit'
-require 'yaml/dbm'
-require 'tmpdir'
-Syck::DBM = YAML::DBM unless defined?(Syck::DBM)
+begin
+  require 'test/unit'
+  require 'yaml/dbm'
+  require 'tmpdir'
+rescue LoadError
+end
 
 module Syck
+  ::Syck::DBM = ::YAML::DBM unless defined?(::Syck::DBM)
+
   class YAMLDBMTest < Test::Unit::TestCase
     def setup
       @engine, YAML::ENGINE.yamler = YAML::ENGINE.yamler, 'syck'
@@ -187,4 +191,4 @@ module Syck
       assert_equal([], @yamldbm.select {false})
     end
   end
-end
+end if defined?(YAML::DBM)