diff --git a/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableObject.cs b/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableObject.cs
index e1f2f36df6f..f1c9b8989b5 100644
--- a/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableObject.cs
+++ b/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableObject.cs
@@ -227,7 +227,7 @@ protected bool SetProperty<T>(T oldValue, T newValue, IEqualityComparer<T> compa
         /// <typeparam name="T">The type of property (or field) to set.</typeparam>
         /// <param name="oldValue">The current property value.</param>
         /// <param name="newValue">The property's value after the change occurred.</param>
-        /// <param name="model">The model </param>
+        /// <param name="model">The model containing the property being updated.</param>
         /// <param name="callback">The callback to invoke to set the target property value, if a change has occurred.</param>
         /// <param name="propertyName">(optional) The name of the property that changed.</param>
         /// <returns><see langword="true"/> if the property was changed, <see langword="false"/> otherwise.</returns>
@@ -236,6 +236,7 @@ protected bool SetProperty<T>(T oldValue, T newValue, IEqualityComparer<T> compa
         /// raised if the current and new value for the target property are the same.
         /// </remarks>
         protected bool SetProperty<TModel, T>(T oldValue, T newValue, TModel model, Action<TModel, T> callback, [CallerMemberName] string? propertyName = null)
+            where TModel : class
         {
             if (EqualityComparer<T>.Default.Equals(oldValue, newValue))
             {
@@ -263,11 +264,12 @@ protected bool SetProperty<TModel, T>(T oldValue, T newValue, TModel model, Acti
         /// <param name="oldValue">The current property value.</param>
         /// <param name="newValue">The property's value after the change occurred.</param>
         /// <param name="comparer">The <see cref="IEqualityComparer{T}"/> instance to use to compare the input values.</param>
-        /// <param name="model">The model </param>
+        /// <param name="model">The model containing the property being updated.</param>
         /// <param name="callback">The callback to invoke to set the target property value, if a change has occurred.</param>
         /// <param name="propertyName">(optional) The name of the property that changed.</param>
         /// <returns><see langword="true"/> if the property was changed, <see langword="false"/> otherwise.</returns>
         protected bool SetProperty<TModel, T>(T oldValue, T newValue, IEqualityComparer<T> comparer, TModel model, Action<TModel, T> callback, [CallerMemberName] string? propertyName = null)
+            where TModel : class
         {
             if (comparer.Equals(oldValue, newValue))
             {
diff --git a/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableRecipient.cs b/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableRecipient.cs
index c4ec80709ce..5a43d09aea4 100644
--- a/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableRecipient.cs
+++ b/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableRecipient.cs
@@ -257,6 +257,7 @@ protected bool SetProperty<T>(T oldValue, T newValue, IEqualityComparer<T> compa
         /// <param name="propertyName">(optional) The name of the property that changed.</param>
         /// <returns><see langword="true"/> if the property was changed, <see langword="false"/> otherwise.</returns>
         protected bool SetProperty<TModel, T>(T oldValue, T newValue, TModel model, Action<TModel, T> callback, bool broadcast, [CallerMemberName] string? propertyName = null)
+            where TModel : class
         {
             bool propertyChanged = SetProperty(oldValue, newValue, model, callback, propertyName);
 
@@ -288,6 +289,7 @@ protected bool SetProperty<TModel, T>(T oldValue, T newValue, TModel model, Acti
         /// <param name="propertyName">(optional) The name of the property that changed.</param>
         /// <returns><see langword="true"/> if the property was changed, <see langword="false"/> otherwise.</returns>
         protected bool SetProperty<TModel, T>(T oldValue, T newValue, IEqualityComparer<T> comparer, TModel model, Action<TModel, T> callback, bool broadcast, [CallerMemberName] string? propertyName = null)
+            where TModel : class
         {
             bool propertyChanged = SetProperty(oldValue, newValue, comparer, model, callback, propertyName);
 
diff --git a/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableValidator.cs b/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableValidator.cs
index a1c20d82817..2a96ab7b837 100644
--- a/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableValidator.cs
+++ b/Microsoft.Toolkit.Mvvm/ComponentModel/ObservableValidator.cs
@@ -170,6 +170,7 @@ protected bool SetProperty<T>(T oldValue, T newValue, IEqualityComparer<T> compa
         /// <param name="propertyName">(optional) The name of the property that changed.</param>
         /// <returns><see langword="true"/> if the property was changed, <see langword="false"/> otherwise.</returns>
         protected bool SetProperty<TModel, T>(T oldValue, T newValue, TModel model, Action<TModel, T> callback, bool validate, [CallerMemberName] string? propertyName = null)
+            where TModel : class
         {
             if (validate)
             {
@@ -199,6 +200,7 @@ protected bool SetProperty<TModel, T>(T oldValue, T newValue, TModel model, Acti
         /// <param name="propertyName">(optional) The name of the property that changed.</param>
         /// <returns><see langword="true"/> if the property was changed, <see langword="false"/> otherwise.</returns>
         protected bool SetProperty<TModel, T>(T oldValue, T newValue, IEqualityComparer<T> comparer, TModel model, Action<TModel, T> callback, bool validate, [CallerMemberName] string? propertyName = null)
+            where TModel : class
         {
             if (validate)
             {