diff --git a/ChangeLog b/ChangeLog
index 07a3327f59..224c2ea6d2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Mar 11 22:22:38 2014  Kazuki Tsujimoto  <kazuki@callcc.net>
+
+	* test/objspace/test_objspace.rb (TestObjSpace#test_dump_uninitialized_file):
+	  remove dependency on json library.
+
 Tue Mar 11 10:55:10 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* README.EXT{,.ja} (Appendix B): update contents of `ruby_options`
diff --git a/test/objspace/test_objspace.rb b/test/objspace/test_objspace.rb
index ea89a87e18..7c4dc0bff9 100644
--- a/test/objspace/test_objspace.rb
+++ b/test/objspace/test_objspace.rb
@@ -268,13 +268,12 @@ class TestObjSpace < Test::Unit::TestCase
   end
 
   def test_dump_uninitialized_file
-    assert_in_out_err(%[-robjspace], <<-RUBY) do |output, error|
+    assert_in_out_err(%[-robjspace], <<-RUBY) do |(output), (error)|
       puts ObjectSpace.dump(File.allocate)
     RUBY
-      assert_equal [], error
-      json = JSON.load(output.join)
-      assert_equal "FILE", json["type"]
-      assert_nil json["fd"]
+      assert_nil error
+      assert_match /"type":"FILE"/, output
+      assert_not_match /"fd":/, output
     end
   end
 end