diff --git a/custom/ports.tf b/custom/ports.tf
index 7c53124..7b5c97e 100644
--- a/custom/ports.tf
+++ b/custom/ports.tf
@@ -9,11 +9,11 @@ locals {
 
   p_fields = ["from", "to", "proto", "description", "cidr"]
   #  p_map    = length(var.ingress_port_list) > 0 ? [for p in local.ports : zipmap(local.p_fields, p)] : var.ingress_port_map
-  port_source = length(var.ingress_port_list) > 0 ? var.ingress_port_list : local.ports
+  port_source = length(var.ingress_port_list) > 0 ? tolist(var.ingress_port_list) : tolist(local.ports)
   p_map       = [for p in local.port_source : zipmap(local.p_fields, p)]
-  port_map    = { "external" = compact(concat(local.p_map, var.ingress_port_map)) }
+  port_map    = { "external" = compact(concat(local.p_map, tolist(var.ingress_port_map))) }
 
   p_self_fields  = ["from", "to", "proto", "description"]
   self_port_list = length(var.ingress_self_port_list) > 0 ? [for p in var.ingress_self_port_list : zipmap(local.p_self_fields, p)] : local._defaults["self_port_list"]
-  self_port_map  = compact(concat(local.self_port_list, var.ingress_self_port_map))
+  self_port_map  = compact(concat(local.self_port_list, tolist(var.ingress_self_port_map)))
 }