diff --git a/devstack/plugin.sh b/devstack/plugin.sh
index 5d5287a..289cb58 100644
--- a/devstack/plugin.sh
+++ b/devstack/plugin.sh
@@ -162,15 +162,8 @@ function configure_tobiko_neutron {
     echo_summary "Write [neutron] section to ${TOBIKO_CONF_FILE}"
     local tobiko_conf_file=$1
 
-    if [ -n "${TOBIKO_NEUTRON_EXTERNAL_NETWORK}" ]; then
-        # enable DHCP on IPv4 subnet of external network
-        openstack subnet list --no-dhcp --ip-version 4 -c ID -f value \
-            --network "${TOBIKO_NEUTRON_EXTERNAL_NETWORK}" | \
-            xargs -r -n 1 openstack subnet set --dhcp
-        iniset "${tobiko_conf_file}" neutron external_network \
-            "${TOBIKO_NEUTRON_EXTERNAL_NETWORK}"
-    fi
-
+    iniset_nonempty "${tobiko_conf_file}" neutron external_network \
+        "${TOBIKO_NEUTRON_EXTERNAL_NETWORK}"
     iniset_nonempty "${tobiko_conf_file}" neutron floating_network \
         "${TOBIKO_NEUTRON_FLOATING_NETWORK}"
     iniset_nonempty "${tobiko_conf_file}" neutron ipv4_dns_nameservers \