diff --git a/tools/tox_install.sh b/tools/tox_install.sh
index 94723216..465cf4f9 100755
--- a/tools/tox_install.sh
+++ b/tools/tox_install.sh
@@ -26,6 +26,7 @@ if [ $neutron_installed -eq 0 ]; then
 elif [ -x "$ZUUL_CLONER" ]; then
     echo "ZUUL CLONER" > /tmp/tox_install.txt
     cd /tmp
+    export ZUUL_BRANCH=${ZUUL_BRANCH-$BRANCH}
     $ZUUL_CLONER --cache-dir \
         /opt/git \
         git://git.openstack.org \