diff --git a/src/Aspire.Hosting/ApplicationModel/InputAnnotation.cs b/src/Aspire.Hosting/ApplicationModel/InputAnnotation.cs
index a9cb090e97..e35e4b2d27 100644
--- a/src/Aspire.Hosting/ApplicationModel/InputAnnotation.cs
+++ b/src/Aspire.Hosting/ApplicationModel/InputAnnotation.cs
@@ -18,6 +18,7 @@ public sealed class InputAnnotation : IResourceAnnotation, IValueProvider
 {
     private string? _value;
     private bool _hasValue;
+    private Func<string>? _valueGetter;
 
     /// <summary>
     /// Initializes a new instance of <see cref="InputAnnotation"/>.
@@ -45,23 +46,28 @@ public InputAnnotation(string name, bool secret = false)
     /// </summary>
     public InputDefault? Default { get; set; }
 
-    internal Func<string>? ValueGetter { get; set; }
-
-    ValueTask<string?> IValueProvider.GetValueAsync(CancellationToken cancellationToken)
+    internal string? Value
     {
-        if (!_hasValue)
+        get
         {
-            _value = GenerateValue();
-            _hasValue = true;
+            if (!_hasValue)
+            {
+                _value = GenerateValue();
+                _hasValue = true;
+            }
+            return _value;
         }
-        return new(_value);
     }
 
+    ValueTask<string?> IValueProvider.GetValueAsync(CancellationToken cancellationToken) => new(Value);
+
+    internal void SetValueGetter(Func<string> valueGetter) => _valueGetter = valueGetter;
+
     private string GenerateValue()
     {
-        if (ValueGetter is not null)
+        if (_valueGetter is not null)
         {
-            return ValueGetter();
+            return _valueGetter();
         }
 
         if (Default is null)
diff --git a/src/Aspire.Hosting/ApplicationModel/ParameterResource.cs b/src/Aspire.Hosting/ApplicationModel/ParameterResource.cs
index 1d99a9b367..88e7ed25e1 100644
--- a/src/Aspire.Hosting/ApplicationModel/ParameterResource.cs
+++ b/src/Aspire.Hosting/ApplicationModel/ParameterResource.cs
@@ -19,7 +19,8 @@ public sealed class ParameterResource : Resource, IManifestExpressionProvider, I
     public ParameterResource(string name, Func<string> callback, bool secret = false) : base(name)
     {
         _valueInput = new InputAnnotation("value", secret);
-        _valueInput.ValueGetter = callback;
+        _valueInput.SetValueGetter(callback);
+
         Annotations.Add(_valueInput);
 
         ValueInputReference = new InputReference(this, "value");
@@ -28,7 +29,7 @@ public ParameterResource(string name, Func<string> callback, bool secret = false
     /// <summary>
     /// Gets the value of the parameter.
     /// </summary>
-    public string Value => _valueInput.ValueGetter!();
+    public string Value => _valueInput.Value ?? throw new InvalidOperationException("A Parameter's value cannot be null.");
 
     /// <summary>
     /// Gets a value indicating whether the parameter is secret.