diff --git a/scripts/WmiNamespaceDescendants.ps1 b/scripts/WmiNamespaceDescendants.ps1
index 394807fe..bc8a7601 100644
--- a/scripts/WmiNamespaceDescendants.ps1
+++ b/scripts/WmiNamespaceDescendants.ps1
@@ -52,6 +52,9 @@ function Get-WelaWmiDescendants {
     try {
         if($Namespace -cnotmatch '^root(\\[A-Za-z_][A-Za-z0-9_]{0,63}){1,8}$'){throw 'An exact local WMI namespace is required.'}
         $root=Get-WelaWmiNamespaceSnapshot $Namespace
+        if($root.Namespace -cne $Namespace -or -not $root.DescriptorJson -or -not $root.DescriptorMof){throw 'Incomplete selected namespace descriptor.'}
+        $bytes=[Text.Encoding]::UTF8.GetByteCount($root.DescriptorJson+$root.DescriptorMof)
+        if($bytes -gt 2097152){throw 'WMI tree descriptor evidence exceeds two MiB.'}
         $queue.Enqueue([pscustomobject]@{Namespace=$Namespace;Depth=0;ProtectedBarrier=$false})
         $null=$seen.Add($Namespace)
         while($queue.Count){
diff --git a/tests/WmiNamespaceDescendants.Tests.ps1 b/tests/WmiNamespaceDescendants.Tests.ps1
index e123c08d..532c7d3e 100644
--- a/tests/WmiNamespaceDescendants.Tests.ps1
+++ b/tests/WmiNamespaceDescendants.Tests.ps1
@@ -53,6 +53,8 @@ try{
  Assert ((Get-WelaWmiDescendants 'root\default').Status -eq 'Incomplete') 'Depth overflow fails rather than truncates.'
  Reset;$script:tree['root\default\A'].Opaque='x'*2097153
  Assert ((Get-WelaWmiDescendants 'root\default').Status -eq 'Incomplete') 'Serialized descriptor budget enforced.'
+ Reset;$script:tree['root\default'].Opaque='x'*2097153
+ Assert ((Get-WelaWmiDescendants 'root\default').Status -eq 'Incomplete') 'The selected root also counts toward the descriptor budget.'
  Reset
  $p=@(Get-WelaWmiAuditPlan -Namespace 'root\default' -IncludeChildren)
  $c=New-WelaConfigurationContext -Auto -DryRun -BackupPath $temp