diff --git a/ChangeLog b/ChangeLog
index b3b9e4a221..134cb006eb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,8 +1,14 @@
-Mon Nov 29 05:58:58 2010  Koichi Sasada  <ko1@atdot.net>
+Sun Nov 28 22:13:39 2010  Koichi Sasada  <ko1@atdot.net>
+
+	* thread_pthread.c (NATIVE_MUTEX_LOCK_DEBUG): move and use it.
+
+	* ChangeLog: fix my timezone.
+
+Mon Nov 28 21:58:58 2010  Koichi Sasada  <ko1@atdot.net>
 
 	* thread_pthread.c: remove pthread_atfork().
 
-Mon Nov 29 05:54:22 2010  Koichi Sasada  <ko1@atdot.net>
+Mon Nov 28 21:54:22 2010  Koichi Sasada  <ko1@atdot.net>
 
 	* thread_pthread.c (native_cond_*): Check return code.
 	  (Some OSs except Linux return error code).
diff --git a/thread_pthread.c b/thread_pthread.c
index c5f04e4d9e..a7def4d42f 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -153,10 +153,12 @@ gvl_atfork(rb_vm_t *vm)
     gvl_acquire(vm, GET_THREAD());
 }
 
+#define NATIVE_MUTEX_LOCK_DEBUG 0
+
 static void
 mutex_debug(const char *msg, pthread_mutex_t *lock)
 {
-    if (0) {
+    if (NATIVE_MUTEX_LOCK_DEBUG) {
 	int r;
 	static pthread_mutex_t dbglock = PTHREAD_MUTEX_INITIALIZER;
 
@@ -166,8 +168,6 @@ mutex_debug(const char *msg, pthread_mutex_t *lock)
     }
 }
 
-#define NATIVE_MUTEX_LOCK_DEBUG 1
-
 static void
 native_mutex_lock(pthread_mutex_t *lock)
 {