diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 7b158b1eb..dcef6f846 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,7 @@
+2007-08-10  Corinna Vinschen  <corinna@vinschen.de>
+
+	* path.cc (fillout_mntent): Fix calculation of unicode buffer size.
+
 2007-08-10  Corinna Vinschen  <corinna@vinschen.de>
 
 	* syscalls.cc (rename): Check oldpath and newpath for trailing dir
diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index 380029cf0..2374c1cb7 100644
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -2625,7 +2625,8 @@ fillout_mntent (const char *native_path, const char *posix_path, unsigned flags)
 
   fs_info mntinfo;
   UNICODE_STRING unat;
-  size_t size = (strlen (native_path) + 1) * sizeof (WCHAR);
+  /* Size must allow prepending the native NT path prefixes. */
+  size_t size = (strlen (native_path) + 10) * sizeof (WCHAR);
   RtlInitEmptyUnicodeString (&unat, (PWSTR) alloca (size), size);
   get_nt_native_path (native_path, unat);
   mntinfo.update (&unat, true);  /* this pulls from a cache, usually. */