diff --git a/locals.tf b/locals.tf
index fd4e513..0d2750c 100644
--- a/locals.tf
+++ b/locals.tf
@@ -15,6 +15,8 @@ locals {
 
   windows_nodes = (length([for v in local.node_pools : v if lower(v.os_type) == "windows"]) > 0 ? true : false)
 
+  api_server_authorized_ip_ranges = (var.api_server_authorized_ip_ranges == null ? null : values(var.api_server_authorized_ip_ranges))
+
   invalid_node_pool_attributes = join(",", flatten([for np in values(var.node_pools) : [for k, v in np : k if !(contains(keys(var.node_pool_defaults), k))]]))
   validate_node_pool_attributes = (length(local.invalid_node_pool_attributes) > 0 ?
   file("ERROR: invalid node pool attribute:  ${local.invalid_node_pool_attributes}") : null)
diff --git a/main.tf b/main.tf
index f23c0e7..2dbf19a 100644
--- a/main.tf
+++ b/main.tf
@@ -72,7 +72,7 @@ resource "azurerm_kubernetes_cluster" "aks" {
     }
   }
 
-  api_server_authorized_ip_ranges = values(var.api_server_authorized_ip_ranges)
+  api_server_authorized_ip_ranges = local.api_server_authorized_ip_ranges
 
   addon_profile {
     kube_dashboard {