diff --git a/main.tf b/main.tf
index 3610157..1a64a74 100644
--- a/main.tf
+++ b/main.tf
@@ -81,7 +81,7 @@ module "container" {
   source  = "terraform-google-modules/container-vm/google"
   version = "3.1.1"
 
-  cos_image_name = element(split("/", var.machine_image), length(split("/", var.machine_image)) -1)
+  cos_image_name = element(split("/", var.machine_image), length(split("/", var.machine_image)) - 1)
 
   container = {
     image = var.image