diff --git a/jenkins-unittests.sh b/jenkins-unittests.sh
index 6b0c296cff..4c2f103e80 100755
--- a/jenkins-unittests.sh
+++ b/jenkins-unittests.sh
@@ -25,5 +25,6 @@ rm .coverage* || echo "No coverage files to remove"
 tox --notest -e py27
 TOX_BIN=$WORKSPACE/.tox/py27/bin
 python synapse/python_dependencies.py | xargs -n1 $TOX_BIN/pip install
+$TOX_BIN/pip install lxml
 
 tox -e py27