diff --git a/README.md b/README.md
index 1717ef319baa67cf805efecd98f69071b4de66d1..689d3c173137105577c57e21fb61dcf380d4881f 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,8 @@ License:
 
 The parser is avialable under a two-clause BSD license.
 
-It uses three other projects:
+It uses four other projects:
+* Forty generates a [JastAdd](https://bitbucket.org/jastadd/jastadd2) AST. JastAdd is available under a modified BSD license.
 * The test cases for the parser originate from [OpenFortran](https://github.com/OpenFortranProject/open-fortran-parser/) and are available under a BSD license.
 * The debugging program [DrAST](https://bitbucket.org/jastadd/drast) from  is also available under a BSD license.
 * The [RATS!](https://cs.nyu.edu/rgrimm/xtc) parser generator is used. Its license is GPL, but the runtime libraries required are LGPL.