diff --git a/ChangeLog b/ChangeLog
index 02c198ee6d..81460e0865 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Jul 31 13:18:30 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* include/ruby/ruby.h (struct RString): size of ary must be
+	  RSTRING_EMBED_LEN_MAX + 1.
+
 Thu Jul 31 12:23:53 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* pack.c (pack_unpack): upper half of hexdigits has never been used.
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index db3253da42..bea12e9246 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -515,7 +515,7 @@ struct RString {
 		VALUE shared;
 	    } aux;
 	} heap;
-	char ary[RSTRING_EMBED_LEN_MAX];
+	char ary[RSTRING_EMBED_LEN_MAX + 1];
     } as;
 };
 #define RSTRING_NOEMBED FL_USER1