diff --git a/tox.ini b/tox.ini
index d9d759e9..8763c963 100644
--- a/tox.ini
+++ b/tox.ini
@@ -15,6 +15,7 @@ deps =
     Markdown
     BeautifulSoup4
     typogrify
+    lxml
 
 [testenv:py33]
 deps =
@@ -23,3 +24,4 @@ deps =
     BeautifulSoup4
     git+https://github.com/dmdm/smartypants.git#egg=smartypants
     git+https://github.com/dmdm/typogrify.git@py3k#egg=typogrify
+    lxml