diff --git a/modules/compute-vm/resource-policies.tf b/modules/compute-vm/resource-policies.tf
index de816c15fc..743e1e3350 100644
--- a/modules/compute-vm/resource-policies.tf
+++ b/modules/compute-vm/resource-policies.tf
@@ -141,9 +141,7 @@ resource "google_compute_resource_policy" "snapshot" {
 }
 
 resource "google_compute_disk_resource_policy_attachment" "boot" {
-  for_each = var.boot_disk.snapshot_schedule != null ? {
-    for i, v in var.boot_disk.snapshot_schedule : i => v
-  } : {}
+  for_each = var.boot_disk.snapshot_schedule != null ? toset(var.boot_disk.snapshot_schedule) : []
   project  = var.project_id
   zone     = var.zone
   name = try(