diff --git a/CHANGELOG.md b/CHANGELOG.md
index cf23883..6c862b0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   any `IDictionary` instead of only exact `System.Collections.Hashtable`, so
   configuration built via `ConvertFrom-Json -AsHashtable` (which returns an
   `OrderedHashtable`) and other ordered/generic dictionaries bind correctly.
+- `PropertySetTransformAttribute` no longer calls the broken, argument-less
+  `Read-PropertySet` when `-PropertySet` is omitted (that call could never
+  bind and always threw). `-PropertySet` is now a mandatory parameter on
+  `Test-FeatureFlag`, matching `Test-Condition`, so the missing value is
+  reported with a clear mandatory-parameter error instead. (#84)
 
 ## [1.0.0] 2026-06-05
 
diff --git a/Gatekeeper/Classes/Property.ps1 b/Gatekeeper/Classes/Property.ps1
index 85c71fb..afb68a7 100644
--- a/Gatekeeper/Classes/Property.ps1
+++ b/Gatekeeper/Classes/Property.ps1
@@ -186,7 +186,7 @@ class PropertySetTransformAttribute : System.Management.Automation.ArgumentTrans
 
     [object] Transform([System.Management.Automation.EngineIntrinsics]$engineIntrinsics, [object] $inputData) {
         if ($null -eq $inputData) {
-            return $(Read-PropertySet)
+            return $null
         }
         if ($inputData -is [PropertySet]) {
             return $inputData
diff --git a/Gatekeeper/Public/Test-FeatureFlag.ps1 b/Gatekeeper/Public/Test-FeatureFlag.ps1
index 76f8ed3..632fe5e 100644
--- a/Gatekeeper/Public/Test-FeatureFlag.ps1
+++ b/Gatekeeper/Public/Test-FeatureFlag.ps1
@@ -36,6 +36,8 @@
         [FeatureFlag]
         [FeatureFlagTransformAttribute()]
         $FeatureFlag,
+        [Parameter(Mandatory)]
+        [ValidateNotNull()]
         [PropertySet]
         [PropertySetTransformAttribute()]
         $PropertySet,
diff --git a/docs/en-US/Test-FeatureFlag.md b/docs/en-US/Test-FeatureFlag.md
index 3a80470..1ee18af 100644
--- a/docs/en-US/Test-FeatureFlag.md
+++ b/docs/en-US/Test-FeatureFlag.md
@@ -13,7 +13,7 @@ Checks if the current machine's context will pass the feature flag rules.
 ## SYNTAX
 
 ```
-Test-FeatureFlag [-FeatureFlag] <FeatureFlag> [[-PropertySet] <PropertySet>] [-Context] <Hashtable>
+Test-FeatureFlag [-FeatureFlag] <FeatureFlag> [-PropertySet] <PropertySet> [-Context] <Hashtable>
  [-ProgressAction <ActionPreference>] [<CommonParameters>]
 ```
 
@@ -60,7 +60,7 @@ Type: PropertySet
 Parameter Sets: (All)
 Aliases:
 
-Required: False
+Required: True
 Position: 2
 Default value: None
 Accept pipeline input: False