diff --git a/ChangeLog b/ChangeLog
index a212bd77a2..71f1e4366b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Wed Sep 10 03:12:12 2014  CHIKANAGA Tomoyuki  <nagachika@ruby-lang.org>
+
+	* gc.c (init_mark_stack): MEMZERO() receive type as 2nd argument instead
+	  of size.
+	  Coverity Scan found this bug.
+
 Tue Sep  9 21:55:39 2014  Masaki Suketa <masaki.suketa@nifty.ne.jp>
 
 	* ext/win32ole/sample/excel2.rb: remove some commented-out code.
diff --git a/gc.c b/gc.c
index 08fa320335..03e7b8fb26 100644
--- a/gc.c
+++ b/gc.c
@@ -3544,7 +3544,7 @@ init_mark_stack(mark_stack_t *stack)
 {
     int i;
 
-    MEMZERO(stack, sizeof(mark_stack_t), 1);
+    MEMZERO(stack, mark_stack_t, 1);
     stack->index = stack->limit = STACK_CHUNK_SIZE;
     stack->cache_size = 0;