diff --git a/Dockerfile b/Dockerfile
index 5d2a005..bce4590 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 # Pull the base image with given version.
-ARG BUILD_TERRAFORM_VERSION="0.13.5"
+ARG BUILD_TERRAFORM_VERSION="0.14.4"
 FROM mcr.microsoft.com/terraform-test:${BUILD_TERRAFORM_VERSION}
 
 ARG MODULE_NAME="terraform-azurerm-compute"
diff --git a/main.tf b/main.tf
index 5d9c897..c62f424 100644
--- a/main.tf
+++ b/main.tf
@@ -30,7 +30,7 @@ resource "azurerm_storage_account" "vm-sa" {
 }
 
 resource "azurerm_virtual_machine" "vm-linux" {
-  count                         = ! contains(list(var.vm_os_simple, var.vm_os_offer), "WindowsServer") && ! var.is_windows_image ? var.nb_instances : 0
+  count                         = ! contains(tolist([var.vm_os_simple, var.vm_os_offer]), "WindowsServer") && ! var.is_windows_image ? var.nb_instances : 0
   name                          = "${var.vm_hostname}-vmLinux-${count.index}"
   resource_group_name           = data.azurerm_resource_group.vm.name
   location                      = coalesce(var.location, data.azurerm_resource_group.vm.location)
@@ -139,7 +139,7 @@ resource "azurerm_virtual_machine" "vm-linux" {
 }
 
 resource "azurerm_virtual_machine" "vm-windows" {
-  count                         = (var.is_windows_image || contains(list(var.vm_os_simple, var.vm_os_offer), "WindowsServer")) ? var.nb_instances : 0
+  count                         = (var.is_windows_image || contains(tolist([var.vm_os_simple, var.vm_os_offer]), "WindowsServer")) ? var.nb_instances : 0
   name                          = "${var.vm_hostname}-vmWindows-${count.index}"
   resource_group_name           = data.azurerm_resource_group.vm.name
   location                      = coalesce(var.location, data.azurerm_resource_group.vm.location)
@@ -295,7 +295,7 @@ resource "azurerm_network_interface" "vm" {
     name                          = "${var.vm_hostname}-ip-${count.index}"
     subnet_id                     = var.vnet_subnet_id
     private_ip_address_allocation = "Dynamic"
-    public_ip_address_id          = length(azurerm_public_ip.vm.*.id) > 0 ? element(concat(azurerm_public_ip.vm.*.id, list("")), count.index) : ""
+    public_ip_address_id          = length(azurerm_public_ip.vm.*.id) > 0 ? element(concat(azurerm_public_ip.vm.*.id, tolist([""])), count.index) : ""
   }
 
   tags = var.tags