diff --git a/ChangeLog b/ChangeLog
index ec6ad46ef9..b5119c8508 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Feb 15 20:34:53 2011  Tanaka Akira  <akr@fsij.org>
+
+	* array.c (ary_join_1): fix array size.
+
 Tue Feb 15 19:43:23 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* configure.in: fix and resubmit r30621. [ruby-dev:43203]
diff --git a/array.c b/array.c
index d505e5a3c4..bdeb768118 100644
--- a/array.c
+++ b/array.c
@@ -1650,7 +1650,7 @@ ary_join_1(VALUE obj, VALUE ary, VALUE sep, long i, VALUE result, int *first)
 		rb_raise(rb_eArgError, "recursive array join");
 	    }
 	    else {
-		VALUE args[3];
+		VALUE args[4];
 
 		args[0] = val;
 		args[1] = sep;