diff --git a/fast/stages/0-bootstrap/README.md b/fast/stages/0-bootstrap/README.md
index 51e59a8a..1e80e285 100644
--- a/fast/stages/0-bootstrap/README.md
+++ b/fast/stages/0-bootstrap/README.md
@@ -643,9 +643,9 @@ The `fast_features` variable consists of 4 toggles:
 | [log_sinks](variables.tf#L183) | Org-level log sinks, in name => {type, filter} format. | <code title="map&#40;object&#40;&#123;&#10;  filter &#61; string&#10;  type   &#61; string&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code title="&#123;&#10;  audit-logs &#61; &#123;&#10;    filter &#61; &#34;logName:&#92;&#34;&#47;logs&#47;cloudaudit.googleapis.com&#37;2Factivity&#92;&#34; OR logName:&#92;&#34;&#47;logs&#47;cloudaudit.googleapis.com&#37;2Fsystem_event&#92;&#34; OR protoPayload.metadata.&#64;type&#61;&#92;&#34;type.googleapis.com&#47;google.cloud.audit.TransparencyLog&#92;&#34;&#34;&#10;    type   &#61; &#34;logging&#34;&#10;  &#125;&#10;  vpc-sc &#61; &#123;&#10;    filter &#61; &#34;protoPayload.metadata.&#64;type&#61;&#92;&#34;type.googleapis.com&#47;google.cloud.audit.VpcServiceControlAuditMetadata&#92;&#34;&#34;&#10;    type   &#61; &#34;logging&#34;&#10;  &#125;&#10;  workspace-audit-logs &#61; &#123;&#10;    filter &#61; &#34;logName:&#92;&#34;&#47;logs&#47;cloudaudit.googleapis.com&#37;2Fdata_access&#92;&#34; and protoPayload.serviceName:&#92;&#34;login.googleapis.com&#92;&#34;&#34;&#10;    type   &#61; &#34;logging&#34;&#10;  &#125;&#10;&#125;">&#123;&#8230;&#125;</code> |  |
 | [org_policies_config](variables.tf#L212) | Organization policies customization. | <code title="object&#40;&#123;&#10;  constraints &#61; optional&#40;object&#40;&#123;&#10;    allowed_policy_member_domains &#61; optional&#40;list&#40;string&#41;, &#91;&#93;&#41;&#10;  &#125;&#41;, &#123;&#125;&#41;&#10;  import_defaults &#61; optional&#40;bool, false&#41;&#10;  tag_name        &#61; optional&#40;string, &#34;org-policies&#34;&#41;&#10;  tag_values &#61; optional&#40;map&#40;object&#40;&#123;&#10;    description &#61; optional&#40;string, &#34;Managed by the Terraform organization module.&#34;&#41;&#10;    iam         &#61; optional&#40;map&#40;list&#40;string&#41;&#41;, &#123;&#125;&#41;&#10;    id          &#61; optional&#40;string&#41;&#10;  &#125;&#41;&#41;, &#123;&#125;&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>&#123;&#125;</code> |  |
 | [outputs_location](variables.tf#L238) | Enable writing provider, tfvars and CI/CD workflow files to local filesystem. Leave null to disable. | <code>string</code> |  | <code>null</code> |  |
-| [project_parent_ids](variables.tf#L253) | Optional parents for projects created here in folders/nnnnnnn format. Null values will use the organization as parent. | <code title="object&#40;&#123;&#10;  automation &#61; string&#10;  billing    &#61; string&#10;  logging    &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code title="&#123;&#10;  automation &#61; null&#10;  billing    &#61; null&#10;  logging    &#61; null&#10;&#125;">&#123;&#8230;&#125;</code> |  |
-| [workforce_identity_providers](variables.tf#L268) | Workforce Identity Federation pools. | <code title="map&#40;object&#40;&#123;&#10;  attribute_condition &#61; optional&#40;string&#41;&#10;  issuer              &#61; string&#10;  display_name        &#61; string&#10;  description         &#61; string&#10;  disabled            &#61; optional&#40;bool, false&#41;&#10;  saml &#61; optional&#40;object&#40;&#123;&#10;    idp_metadata_xml &#61; string&#10;  &#125;&#41;, null&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |  |
-| [workload_identity_providers](variables.tf#L284) | Workload Identity Federation pools. The `cicd_repositories` variable references keys here. | <code title="map&#40;object&#40;&#123;&#10;  attribute_condition &#61; optional&#40;string&#41;&#10;  issuer              &#61; string&#10;  custom_settings &#61; optional&#40;object&#40;&#123;&#10;    issuer_uri &#61; optional&#40;string&#41;&#10;    audiences  &#61; optional&#40;list&#40;string&#41;, &#91;&#93;&#41;&#10;    jwks_json  &#61; optional&#40;string&#41;&#10;  &#125;&#41;, &#123;&#125;&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |  |
+| [project_parent_ids](variables.tf#L253) | Optional parents for projects created here in folders/nnnnnnn format. Null values will use the organization as parent. | <code title="object&#40;&#123;&#10;  automation &#61; optional&#40;string&#41;&#10;  billing    &#61; optional&#40;string&#41;&#10;  logging    &#61; optional&#40;string&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>&#123;&#125;</code> |  |
+| [workforce_identity_providers](variables.tf#L264) | Workforce Identity Federation pools. | <code title="map&#40;object&#40;&#123;&#10;  attribute_condition &#61; optional&#40;string&#41;&#10;  issuer              &#61; string&#10;  display_name        &#61; string&#10;  description         &#61; string&#10;  disabled            &#61; optional&#40;bool, false&#41;&#10;  saml &#61; optional&#40;object&#40;&#123;&#10;    idp_metadata_xml &#61; string&#10;  &#125;&#41;, null&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |  |
+| [workload_identity_providers](variables.tf#L280) | Workload Identity Federation pools. The `cicd_repositories` variable references keys here. | <code title="map&#40;object&#40;&#123;&#10;  attribute_condition &#61; optional&#40;string&#41;&#10;  issuer              &#61; string&#10;  custom_settings &#61; optional&#40;object&#40;&#123;&#10;    issuer_uri &#61; optional&#40;string&#41;&#10;    audiences  &#61; optional&#40;list&#40;string&#41;, &#91;&#93;&#41;&#10;    jwks_json  &#61; optional&#40;string&#41;&#10;  &#125;&#41;, &#123;&#125;&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |  |
 
 ## Outputs
 
diff --git a/fast/stages/0-bootstrap/variables.tf b/fast/stages/0-bootstrap/variables.tf
index d2d47a1f..d8536fc2 100644
--- a/fast/stages/0-bootstrap/variables.tf
+++ b/fast/stages/0-bootstrap/variables.tf
@@ -253,15 +253,11 @@ variable "prefix" {
 variable "project_parent_ids" {
   description = "Optional parents for projects created here in folders/nnnnnnn format. Null values will use the organization as parent."
   type = object({
-    automation = string
-    billing    = string
-    logging    = string
+    automation = optional(string)
+    billing    = optional(string)
+    logging    = optional(string)
   })
-  default = {
-    automation = null
-    billing    = null
-    logging    = null
-  }
+  default  = {}
   nullable = false
 }