diff --git a/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableValidator.cs b/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableValidator.cs
index 239feb8c635..58bf60577d1 100644
--- a/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableValidator.cs
+++ b/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableValidator.cs
@@ -80,7 +80,7 @@ protected ObservableValidator()
         /// be used to validate all properties, which will reference the current instance.
         /// </summary>
         /// <param name="items">A set of key/value pairs to make available to consumers.</param>
-        protected ObservableValidator(IDictionary<object, object?> items)
+        protected ObservableValidator(IDictionary<object, object?>? items)
         {
             this.validationContext = new ValidationContext(this, items);
         }
@@ -92,7 +92,7 @@ protected ObservableValidator(IDictionary<object, object?> items)
         /// </summary>
         /// <param name="serviceProvider">An <see cref="IServiceProvider"/> instance to make available during validation.</param>
         /// <param name="items">A set of key/value pairs to make available to consumers.</param>
-        protected ObservableValidator(IServiceProvider serviceProvider, IDictionary<object, object?> items)
+        protected ObservableValidator(IServiceProvider? serviceProvider, IDictionary<object, object?>? items)
         {
             this.validationContext = new ValidationContext(this, serviceProvider, items);
         }