diff --git a/ChangeLog b/ChangeLog
index 659df9c954..aecb21a586 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Jun 27 12:29:37 2014  SHIBATA Hiroshi  <shibata.hiroshi@gmail.com>
+
+	* lib/rubygems/specification.rb: fixed broken condition caused
+	  by removing YAML::ENGINE.
+	* lib/rubygems/package/old.rb: ditto.
+
 Fri Jun 27 05:33:26 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* hash.c (env_shift): fix memory leak on Windows, free environment
diff --git a/lib/rubygems/package/old.rb b/lib/rubygems/package/old.rb
index d74753fa90..31c4111d33 100644
--- a/lib/rubygems/package/old.rb
+++ b/lib/rubygems/package/old.rb
@@ -145,7 +145,7 @@ class Gem::Package::Old < Gem::Package
 
     yaml_error = if RUBY_VERSION < '1.9' then
                    YAML::ParseError
-                 elsif YAML::ENGINE.yamler == 'syck' then
+                 elsif YAML.const_defined?(:ENGINE) && YAML::ENGINE.yamler == 'syck' then
                    YAML::ParseError
                  else
                    YAML::SyntaxError
diff --git a/lib/rubygems/specification.rb b/lib/rubygems/specification.rb
index f4e609a5eb..d760ab4a83 100644
--- a/lib/rubygems/specification.rb
+++ b/lib/rubygems/specification.rb
@@ -2359,7 +2359,8 @@ class Gem::Specification < Gem::BasicSpecification
   end
 
   def to_yaml(opts = {}) # :nodoc:
-    if YAML.const_defined?(:ENGINE) && !YAML::ENGINE.syck? then
+    if (YAML.const_defined?(:ENGINE) && !YAML::ENGINE.syck?) ||
+        (defined?(Psych) && YAML == Psych) then
       # Because the user can switch the YAML engine behind our
       # back, we have to check again here to make sure that our
       # psych code was properly loaded, and load it if not.