diff --git a/mrblib/core_ext.rb b/mrblib/core_ext.rb
new file mode 100644
index 0000000..291e895
--- /dev/null
+++ b/mrblib/core_ext.rb
@@ -0,0 +1,5 @@
+class Object
+  def to_yaml
+    YAML.dump self
+  end
+end
diff --git a/test/yaml.rb b/test/yaml.rb
index 5eaed94..7c9139c 100644
--- a/test/yaml.rb
+++ b/test/yaml.rb
@@ -204,6 +204,12 @@
   assert_equal expected, actual
 end
 
+assert('YAML dump to_yaml') do
+  expected = YAML.dump(['foo', 'bar'])
+  actual = ['foo', 'bar'].to_yaml
+  assert_equal expected, actual
+end
+
 assert('YAML dump multi-byte') do
   expected = {'foo' => 'ふー', 'bar' => 'ばー'}
   actual = YAML.load(YAML.dump(expected))