diff --git a/jenkins-unittests.sh b/jenkins-unittests.sh
index 104d511994..7b56a714a1 100755
--- a/jenkins-unittests.sh
+++ b/jenkins-unittests.sh
@@ -20,6 +20,10 @@ export DUMP_COVERAGE_COMMAND="coverage help"
 # UNSTABLE or FAILURE this build.
 export PEP8SUFFIX="--output-file=violations.flake8.log || echo flake8 finished with status code \$?"
 
+TOX_BIN=$WORKSPACE/.tox/py27/bin
+python synapse/python_dependencies.py | xargs -n1 $TOX_BIN/pip install
+$TOX_BIN/pip install lxml
+
 rm .coverage* || echo "No coverage files to remove"
 
 tox -e py27