diff --git a/ChangeLog b/ChangeLog
index 04a26c37f6..887fc47680 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Aug  4 20:37:56 2012  Narihiro Nakamura  <authornari@gmail.com>
+
+	* gc.c (gc_mark_children): use gc_mark_ptr instead of marking
+	  a object directly.
+
 Sat Aug  4 10:02:03 2012  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* test/ruby/test_alias.rb (test_super_in_aliased_module_method):
diff --git a/gc.c b/gc.c
index c6e1edcbeb..99e0ce53ba 100644
--- a/gc.c
+++ b/gc.c
@@ -1839,7 +1839,6 @@ static void
 gc_mark_children(rb_objspace_t *objspace, VALUE ptr, int lev)
 {
     register RVALUE *obj = RANY(ptr);
-    register uintptr_t *bits;
 
     goto marking;		/* skip */
 
@@ -1847,10 +1846,7 @@ gc_mark_children(rb_objspace_t *objspace, VALUE ptr, int lev)
     obj = RANY(ptr);
     if (rb_special_const_p(ptr)) return; /* special const not marked */
     if (obj->as.basic.flags == 0) return;       /* free cell */
-    bits = GET_HEAP_BITMAP(ptr);
-    if (MARKED_IN_BITMAP(bits, ptr)) return;  /* already marked */
-    MARK_IN_BITMAP(bits, ptr);
-    objspace->heap.live_num++;
+    if (!gc_mark_ptr(objspace, ptr)) return;  /* already marked */
 
   marking:
     if (FL_TEST(obj, FL_EXIVAR)) {