diff --git a/lib/tempest b/lib/tempest
index d677c7e33c..3c37918018 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -64,8 +64,10 @@ BOTO_MATERIALS_PATH="$FILES/images/s3-materials/cirros-${CIRROS_VERSION}"
 
 # Cinder/Volume variables
 TEMPEST_VOLUME_DRIVER=${TEMPEST_VOLUME_DRIVER:-default}
-TEMPEST_VOLUME_VENDOR=${TEMPEST_VOLUME_VENDOR:-"Open Source"}
-TEMPEST_STORAGE_PROTOCOL=${TEMPEST_STORAGE_PROTOCOL:-iSCSI}
+TEMPEST_DEFAULT_VOLUME_VENDOR="Open Source"
+TEMPEST_VOLUME_VENDOR=${TEMPEST_VOLUME_VENDOR:-$TEMPEST_DEFAULT_VOLUME_VENDOR}
+TEMPEST_DEFAULT_STORAGE_PROTOCOL="iSCSI"
+TEMPEST_STORAGE_PROTOCOL=${TEMPEST_STORAGE_PROTOCOL:-$TEMPEST_DEFAULT_STORAGE_PROTOCOL}
 
 # Neutron/Network variables
 IPV6_ENABLED=$(trueorfalse True $IPV6_ENABLED)
@@ -369,8 +371,12 @@ function configure_tempest {
         iniset $TEMPEST_CONFIG volume backend2_name "LVM_iSCSI_2"
     fi
 
-    if [ $TEMPEST_VOLUME_DRIVER != "default" ]; then
+    if [ $TEMPEST_VOLUME_DRIVER != "default" -o \
+        $TEMPEST_VOLUME_VENDOR != $TEMPEST_DEFAULT_VOLUME_VENDOR ]; then
         iniset $TEMPEST_CONFIG volume vendor_name "$TEMPEST_VOLUME_VENDOR"
+    fi
+    if [ $TEMPEST_VOLUME_DRIVER != "default" -o \
+        $TEMPEST_STORAGE_PROTOCOL != $TEMPEST_DEFAULT_STORAGE_PROTOCOL ]; then
         iniset $TEMPEST_CONFIG volume storage_protocol $TEMPEST_STORAGE_PROTOCOL
     fi