diff --git a/ChangeLog b/ChangeLog
index 1a8381cc8f..ca818e10fc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Sat Aug 14 17:48:41 2010  Narihiro Nakamura  <authorNari@gmail.com>
+
+	* test/objspace/test_objspace.rb: added test for objspace.
+
+	* ext/objspace/objspace.c: considers T_ZOMBIE by lazy sweep GC.
+
+	* gc.c: considers that dsize was 0. [ruby-dev:42022]
+
 Tue Aug 31 03:42:14 2010  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* string.c (tr_setup_table): fix bug in r29146.
diff --git a/ext/objspace/objspace.c b/ext/objspace/objspace.c
index 817380f83c..ebca2f8487 100644
--- a/ext/objspace/objspace.c
+++ b/ext/objspace/objspace.c
@@ -141,6 +141,9 @@ memsize_of(VALUE obj)
 	}
 	break;
 
+      case T_ZOMBIE:
+	break;
+
       default:
 	rb_bug("objspace/memsize_of(): unknown data type 0x%x(%p)",
 	       BUILTIN_TYPE(obj), (void*)obj);
diff --git a/gc.c b/gc.c
index 25fcc3db5a..564d260266 100644
--- a/gc.c
+++ b/gc.c
@@ -1145,7 +1145,7 @@ rb_data_typed_object_alloc(VALUE klass, void *datap, const rb_data_type_t *type)
 size_t
 rb_objspace_data_type_memsize(VALUE obj)
 {
-    if (RTYPEDDATA_P(obj)) {
+    if (RTYPEDDATA_P(obj) && RTYPEDDATA_TYPE(obj)->dsize) {
 	return RTYPEDDATA_TYPE(obj)->dsize(RTYPEDDATA_DATA(obj));
     }
     else {
diff --git a/test/objspace/test_objspace.rb b/test/objspace/test_objspace.rb
new file mode 100644
index 0000000000..cfdb485747
--- /dev/null
+++ b/test/objspace/test_objspace.rb
@@ -0,0 +1,44 @@
+require "test/unit"
+require "objspace"
+
+class TestObjSpace < Test::Unit::TestCase
+  def test_memsize_of
+    assert_equal(0, ObjectSpace.memsize_of(true))
+    assert_kind_of(Integer, ObjectSpace.memsize_of(Object.new))
+    assert_kind_of(Integer, ObjectSpace.memsize_of(Class))
+    assert_kind_of(Integer, ObjectSpace.memsize_of(""))
+    assert_kind_of(Integer, ObjectSpace.memsize_of([]))
+    assert_kind_of(Integer, ObjectSpace.memsize_of({}))
+    assert_kind_of(Integer, ObjectSpace.memsize_of(//))
+    f = File.new(__FILE__)
+    assert_kind_of(Integer, ObjectSpace.memsize_of(f))
+    f.close
+    assert_kind_of(Integer, ObjectSpace.memsize_of(/a/.match("a")))
+    assert_kind_of(Integer, ObjectSpace.memsize_of(Struct.new(:a)))
+  end
+
+  def test_count_objects_size
+    res = ObjectSpace.count_objects_size
+    assert_equal(false, res.empty?)
+    assert_equal(true, res[:TOTAL] > 0)
+    arg = {}
+    ObjectSpace.count_objects_size(arg)
+    assert_equal(false, arg.empty?)
+  end
+
+  def test_count_nodes
+    res = ObjectSpace.count_nodes
+    assert_equal(false, res.empty?)
+    arg = {}
+    ObjectSpace.count_nodes(arg)
+    assert_equal(false, arg.empty?)
+  end
+
+  def test_count_tdata_objects
+    res = ObjectSpace.count_tdata_objects
+    assert_equal(false, res.empty?)
+    arg = {}
+    ObjectSpace.count_tdata_objects(arg)
+    assert_equal(false, arg.empty?)
+  end
+end
diff --git a/version.h b/version.h
index d91b819450..3597dd99cc 100644
--- a/version.h
+++ b/version.h
@@ -1,5 +1,5 @@
 #define RUBY_VERSION "1.9.2"
-#define RUBY_PATCHLEVEL 23
+#define RUBY_PATCHLEVEL 24
 #define RUBY_VERSION_MAJOR 1
 #define RUBY_VERSION_MINOR 9
 #define RUBY_VERSION_TEENY 1