diff --git a/de/heat-templates/scripts/instance_boot.sh b/de/heat-templates/scripts/instance_boot.sh
index e3f66cf..53fb81b 100644
--- a/de/heat-templates/scripts/instance_boot.sh
+++ b/de/heat-templates/scripts/instance_boot.sh
@@ -82,7 +82,7 @@
 
 DEFAULT_INTERFACE=$(ip route show |awk '/default/ {print $5}')
 
-if [[ -z ${CONTROL_NETWORK_CIDR} ]]; then
+if [[ -n ${CONTROL_NETWORK_CIDR} ]]; then
     CONTROL_IP_ADDRESS=$(ip route get ${CONTROL_NETWORK_CIDR%/*} | head -n1 | fgrep -v ' via ' | awk '/ src / {print $6}')
 else
     CONTROL_IP_ADDRESS=$(get_interface_prefix ${DEFAULT_INTERFACE} | awk -F '/' '{print $1}')