diff --git a/main.tf b/main.tf
index 4bcb317..2ecad66 100644
--- a/main.tf
+++ b/main.tf
@@ -71,6 +71,7 @@ resource "azurerm_virtual_machine_scale_set" "vm-linux" {
     ip_configuration {
       name                                   = "IPConfiguration"
       subnet_id                              = "${var.vnet_subnet_id}"
+      primary                                = true
       load_balancer_backend_address_pool_ids = ["${var.load_balancer_backend_address_pool_ids}"]
     }
   }