diff --git a/ohpc-instance/main.tf b/ohpc-instance/main.tf
index c98102a06fa680d1f4adbe86ca09e46c20310ddd..8309ce7e3a7e8c5773d5c195ced8986da62ae6e1 100644
--- a/ohpc-instance/main.tf
+++ b/ohpc-instance/main.tf
@@ -79,12 +79,12 @@ resource "openstack_compute_floatingip_associate_v2" "ohpc" {
 # Attach specific volumes
 resource "openstack_compute_volume_attach_v2" "attach_prod_volume" {
   instance_id = openstack_compute_instance_v2.ohpc.id
-  volume_id   = var.prod_volume
+  volume_id   = TF_VAR_data_volume
 }
 
 resource "openstack_compute_volume_attach_v2" "attach_prod_queue_volume" {
   instance_id = openstack_compute_instance_v2.ohpc.id
-  volume_id   = var.prod_queue_volume
+  volume_id   = TF_VAR_xdmod_queue_data_volume
 }
 output "xdmod_instance_id" {
   value = openstack_compute_instance_v2.ohpc.id