diff --git a/ChangeLog b/ChangeLog
index aec5a58ed5..e1084dd550 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sun Feb 19 11:53:35 2012  Narihiro Nakamura  <authornari@gmail.com>
+
+	* gc.c (gc_clear_mark_on_sweep_slots): uses slot_sweep() for
+	  unsweeped slots, because some dead objects might be marked in
+	  next the mark phase by false pointers.  [ruby-core:42672]
+
 Sun Feb 19 03:00:30 2012  Tanaka Akira  <akr@fsij.org>
 
 	* test/dbm/test_dbm.rb (test_dbmfile_suffix): check magic numbers.
diff --git a/gc.c b/gc.c
index ee7bb84037..3e0cb3e192 100644
--- a/gc.c
+++ b/gc.c
@@ -2627,8 +2627,7 @@ gc_clear_mark_on_sweep_slots(rb_objspace_t *objspace)
     if (objspace->heap.sweep_slots) {
         while (heaps_increment(objspace));
         while (objspace->heap.sweep_slots) {
-            scan = objspace->heap.sweep_slots;
-            gc_clear_slot_bits(scan);
+            slot_sweep(objspace, objspace->heap.sweep_slots);
             objspace->heap.sweep_slots = objspace->heap.sweep_slots->next;
         }
     }