diff --git a/README.md b/README.md
index 270d1e91..ae6e0f31 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ OpenGeoSys5-EGS
 [![BSD License (modified)](http://img.shields.io/badge/license-BSD-blue.svg?style=flat-square)](https://github.com/norihiro-w/ogs5-egs/blob/master/LICENSE.txt)
 [![Travis](https://img.shields.io/travis/norihiro-w/ogs5-egs.svg?style=flat-square)](https://travis-ci.org/norihiro-w/ogs5-egs)
 
-This code is a branch of OpenGeoSys5 specially developed for modeling deep geothermal reservoirs. The code will not support all the features in the official version (https://github.com/ufz/ogs5).
+This code is a branch of OpenGeoSys5 specially developed for modeling deep geothermal reservoirs. The code is based on the OGS official version 5.3.3 and will not support all the features in the official version (https://github.com/ufz/ogs5).
 
 ## OpenGeoSys project ##