diff --git a/main.tf b/main.tf
index 381dd07..71fa7b0 100644
--- a/main.tf
+++ b/main.tf
@@ -145,8 +145,8 @@ resource "aws_elasticsearch_domain" "default" {
     instance_count           = var.instance_count
     instance_type            = var.instance_type
     dedicated_master_enabled = var.dedicated_master_enabled
-    dedicated_master_count   = var.dedicated_master_count
-    dedicated_master_type    = var.dedicated_master_type
+    dedicated_master_count   = var.dedicated_master_enabled ? var.dedicated_master_count : null
+    dedicated_master_type    = var.dedicated_master_enabled ? var.dedicated_master_type : null
     zone_awareness_enabled   = var.zone_awareness_enabled
     warm_enabled             = var.warm_enabled
     warm_count               = var.warm_enabled ? var.warm_count : null