diff --git a/ChangeLog b/ChangeLog
index 856af545c3..b1c51c9f8a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Jul 11 05:38:05 2011  Yutaka Kanemoto  <kanemoto@ruby-lang.org>
+
+	* thread_pthread.c (get_stack): need to adjust stack addr for
+	  [Bug #1813] on AIX.
+
 Mon Jul 11 01:16:27 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* thread_pthread.c (rb_thread_create_timer_thread): removed
diff --git a/thread_pthread.c b/thread_pthread.c
index d4d3bb5de3..13a8b359e1 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -518,6 +518,7 @@ get_stack(void **addr, size_t *size)
 				   &reg, &regsiz));
     *addr = thinfo.__pi_stackaddr;
     *size = thinfo.__pi_stacksize;
+    STACK_DIR_UPPER((void)0, (void)(*addr = (char *)*addr + *size));
 #else
 #error STACKADDR_AVAILABLE is defined but not implemented.
 #endif