diff --git a/README b/README
index 2f29003f..ff216bec 100644
--- a/README
+++ b/README
@@ -27,6 +27,7 @@ General dependencies
 -----
 
 - Python 2.6 (http://www.python.org)
+- lxml, to read and write XML files. (http://codespeak.net/lxml/)
 - Mako, to generate help files. (http://www.makotemplates.org/)
 - PyYaml, for help files and the build system. (http://pyyaml.org/)
 - Nose, to run unit tests. (http://somethingaboutorange.com/mrl/projects/nose/)