diff --git a/packer/ubuntuserver20.04.pkr.hcl b/packer/ubuntuserver20.04.pkr.hcl
index 7b3e35b..08b90af 100644
--- a/packer/ubuntuserver20.04.pkr.hcl
+++ b/packer/ubuntuserver20.04.pkr.hcl
@@ -51,7 +51,7 @@ source "vsphere-iso" "ubuntuserver" {
     "packer/preseed/UbuntuServer20.04/meta-data"
   ]
   cd_label                = "cidata"
-  iso_url                 = var.iso_authenticatedurl
+  iso_url                 = local.iso_authenticatedurl
   iso_checksum            = var.iso_checksum
 
   shutdown_command        = "echo '${var.ssh_password}' | sudo -S shutdown -P now"