diff --git a/routing/variables.tf b/routing/variables.tf
index f967c45..f012727 100644
--- a/routing/variables.tf
+++ b/routing/variables.tf
@@ -27,6 +27,12 @@ variable "enable_nat" {
   default     = false
 }
 
+variable "availability_zones" {
+  description = "AWS Availability Zones to use (by default will use all available)"
+  type        = list(string)
+  default     = []
+}
+
 ###
 ## 
 ## variable "vpc_domain_name" {