diff --git a/ChangeLog b/ChangeLog
index 66fe3c681a..a49c233f8a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun May 25 04:30:45 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* test/ruby/test_modules.rb (remove_json_mixins): change judgment
+	  condition.
+
 Sun May 25 03:54:39 2008  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* test/ruby/test_modules.rb (test_ancestors, test_included_modules):
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index 6e02c557ed..31e4897a29 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -69,7 +69,7 @@ class TestModule < Test::Unit::TestCase
   end
 
   def remove_json_mixins(list)
-    list.reject {|c| c.instance_methods(false).include?(:to_json) }
+    list.reject {|c| c.to_s.start_with?("JSON") }
   end
 
   module Mixin