diff --git a/ChangeLog b/ChangeLog
index 9c99862faa..678735efdf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat Jun 11 14:20:16 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* vm.c (thread_memsize): don't ignore size of th->local_storage.
+
 Sat Jun 11 10:32:46 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* lib/mkmf.rb: should quote arch_hdrdir and libpath for the case
diff --git a/vm.c b/vm.c
index 57cb090922..83d4351fcb 100644
--- a/vm.c
+++ b/vm.c
@@ -1761,7 +1761,7 @@ thread_memsize(const void *ptr)
 	    size += th->stack_size * sizeof(VALUE);
 	}
 	if (th->local_storage) {
-	    st_memsize(th->local_storage);
+	    size += st_memsize(th->local_storage);
 	}
 	return size;
     }