diff --git a/debian/variables.tf b/debian/variables.tf
index fa70210..f08a79d 100644
--- a/debian/variables.tf
+++ b/debian/variables.tf
@@ -3,7 +3,7 @@ variable "name" {
 }
 
 variable "domain_name" {
-  type = string
+  type    = string
   default = null
 }
 
@@ -78,6 +78,11 @@ variable "mac" {
 }
 
 variable "fixed_dns" {
-  type = string
+  type    = string
   default = ""
 }
+
+variable "disk_size" {
+  type    = number
+  default = 1024 * 1024 * 1024 * 15
+}