diff --git a/ChangeLog b/ChangeLog
index abd6d35693..b2885331cd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Aug 29 00:03:13 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* file.c (file_expand_path): check invalid access.
+
 Thu Aug 28 23:55:50 2008  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* strftime.c (rb_strftime): Time.mktime(2000).strftime("%-S") should
diff --git a/file.c b/file.c
index fbbea23282..0cd90afb8b 100644
--- a/file.c
+++ b/file.c
@@ -2734,6 +2734,7 @@ file_expand_path(VALUE fname, VALUE dname, int abs_mode, VALUE result)
 	*p = '/';
     }
 
+    BUFCHECK(bdiff + 1 >= buflen);
     p[1] = 0;
     root = skipprefix(buf);