diff --git a/README.md b/README.md
index 12a38a4..324e923 100755
--- a/README.md
+++ b/README.md
@@ -4,3 +4,4 @@ It is used to collect patches and extensions as pull requests.
 
 The official home page of bibtexbrowser is <http://www.monperrus.net/martin/bibtexbrowser/>.
 
+Bibtexbrowser is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.