diff --git a/ChangeLog b/ChangeLog
index 6e49270ad3..c004c62ff2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Mon Jul 28 20:17:03 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* vm_core.h: move the definition of struct rb_mutex_struct.
+
+	* thread.c: ditto.
+
 Mon Jul 28 18:58:46 2008  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* thread.c (mutex_unlock): fix typo.
diff --git a/thread.c b/thread.c
index c965a657de..c27595a21a 100644
--- a/thread.c
+++ b/thread.c
@@ -62,7 +62,14 @@ static double timeofday(void);
 struct timeval rb_time_interval(VALUE);
 static int rb_thread_dead(rb_thread_t *th);
 
-typedef struct rb_mutex_struct mutex_t;
+typedef struct rb_mutex_struct
+{
+    rb_thread_lock_t lock;
+    rb_thread_cond_t cond;
+    struct rb_thread_struct volatile *th;
+    volatile int cond_waiting, cond_notified;
+    struct rb_mutex_struct *next_mutex;
+} mutex_t;
 
 static void rb_mutex_unlock_all(mutex_t *mutex);
 static void rb_check_deadlock(rb_vm_t *vm);
diff --git a/vm_core.h b/vm_core.h
index 5a97d10edd..88087a7dbc 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -498,15 +498,6 @@ struct rb_thread_struct
     int abort_on_exception;
 };
 
-struct rb_mutex_struct
-{
-    rb_thread_lock_t lock;
-    rb_thread_cond_t cond;
-    struct rb_thread_struct volatile *th;
-    volatile int cond_waiting, cond_notified;
-    struct rb_mutex_struct *next_mutex;
-};
-
 /* iseq.c */
 VALUE rb_iseq_new(NODE*, VALUE, VALUE, VALUE, VALUE);
 VALUE rb_iseq_new_with_bopt(NODE*, VALUE, VALUE, VALUE, VALUE, VALUE);