diff --git a/ChangeLog b/ChangeLog
index 009b85a078..b9ec91c300 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Nov  1 06:20:44 2013  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* thread.c (rb_mutex_struct): reduce rb_mutex_t size by 8 bytes
+	  on 64bit platform. Patch by Eric Wong. [Feature #9068][ruby-core:58114]
+
 Fri Nov  1 01:08:33 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* benchmark/gc/gcbench.rb: print HWM (high water mark) if possible.
diff --git a/thread.c b/thread.c
index ef869c6c28..38a47c8798 100644
--- a/thread.c
+++ b/thread.c
@@ -390,8 +390,8 @@ typedef struct rb_mutex_struct
     rb_nativethread_lock_t lock;
     rb_nativethread_cond_t cond;
     struct rb_thread_struct volatile *th;
-    int cond_waiting;
     struct rb_mutex_struct *next_mutex;
+    int cond_waiting;
     int allow_trap;
 } rb_mutex_t;