diff --git a/src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.net472.approved.txt b/src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.net472.approved.txt
index 0bbd2e99d6..ef382c6fd4 100644
--- a/src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.net472.approved.txt
+++ b/src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.net472.approved.txt
@@ -216,32 +216,32 @@ namespace ReactiveUI
         [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
                 "view",
                 "isViewModel"})]
-        ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
+        ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor
         ;
-        [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
+        [return: System.Runtime.CompilerServices.TupleElementNames(new string?[]?[] {
                 "view",
                 "isViewModel"})]
-        ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
+        ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor
         ;
         System.IDisposable BindTo<TValue, TTarget, TTValue>(System.IObservable<TValue> observedChange, TTarget target, System.Linq.Expressions.Expression<System.Func<TTarget, TTValue>> propertyExpression, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TTarget :  class
         ;
-        ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
+        ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor
         ;
-        ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
+        ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor
         ;
     }
     public interface IPropertyBindingHook
     {
-        bool ExecuteHook(object source, object target, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewModelProperties, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewProperties, ReactiveUI.BindingDirection direction);
+        bool ExecuteHook(object? source, object target, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewModelProperties, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewProperties, ReactiveUI.BindingDirection direction);
     }
     public class IROObservableForProperty : ReactiveUI.ICreatesObservableForProperty, Splat.IEnableLogger
     {
@@ -433,21 +433,21 @@ namespace ReactiveUI
         [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
                 "view",
                 "isViewModel"})]
-        public ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
+        public ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
-        [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
+        [return: System.Runtime.CompilerServices.TupleElementNames(new string?[]?[] {
                 "view",
                 "isViewModel"})]
-        public ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>> Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
+        public ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>> Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
         public System.IDisposable BindTo<TValue, TTarget, TTValue>(System.IObservable<TValue> observedChange, TTarget target, System.Linq.Expressions.Expression<System.Func<TTarget, TTValue>> propertyExpression, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TTarget :  class { }
-        public ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
+        public ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
-        public ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
+        public ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
     }
@@ -456,33 +456,33 @@ namespace ReactiveUI
         [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
                 "view",
                 "isViewModel"})]
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
         [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
                 "view",
                 "isViewModel"})]
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
         [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
                 "view",
                 "isViewModel"})]
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
-        [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
+        [return: System.Runtime.CompilerServices.TupleElementNames(new string?[]?[] {
                 "view",
                 "isViewModel"})]
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
         public static System.IDisposable BindTo<TValue, TTarget, TTValue>(this System.IObservable<TValue> @this, TTarget target, System.Linq.Expressions.Expression<System.Func<TTarget, TTValue>> property, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TTarget :  class { }
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
     }
diff --git a/src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.netcoreapp3.1.approved.txt b/src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.netcoreapp3.1.approved.txt
index 48be053cf6..349ba27f6c 100644
--- a/src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.netcoreapp3.1.approved.txt
+++ b/src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.netcoreapp3.1.approved.txt
@@ -216,32 +216,32 @@ namespace ReactiveUI
         [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
                 "view",
                 "isViewModel"})]
-        ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
+        ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor
         ;
-        [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
+        [return: System.Runtime.CompilerServices.TupleElementNames(new string?[]?[] {
                 "view",
                 "isViewModel"})]
-        ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
+        ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor
         ;
         System.IDisposable BindTo<TValue, TTarget, TTValue>(System.IObservable<TValue> observedChange, TTarget target, System.Linq.Expressions.Expression<System.Func<TTarget, TTValue>> propertyExpression, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TTarget :  class
         ;
-        ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
+        ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor
         ;
-        ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
+        ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor
         ;
     }
     public interface IPropertyBindingHook
     {
-        bool ExecuteHook(object source, object target, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewModelProperties, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewProperties, ReactiveUI.BindingDirection direction);
+        bool ExecuteHook(object? source, object target, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewModelProperties, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewProperties, ReactiveUI.BindingDirection direction);
     }
     public class IROObservableForProperty : ReactiveUI.ICreatesObservableForProperty, Splat.IEnableLogger
     {
@@ -433,21 +433,21 @@ namespace ReactiveUI
         [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
                 "view",
                 "isViewModel"})]
-        public ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
+        public ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
-        [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
+        [return: System.Runtime.CompilerServices.TupleElementNames(new string?[]?[] {
                 "view",
                 "isViewModel"})]
-        public ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>> Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
+        public ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>> Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
         public System.IDisposable BindTo<TValue, TTarget, TTValue>(System.IObservable<TValue> observedChange, TTarget target, System.Linq.Expressions.Expression<System.Func<TTarget, TTValue>> propertyExpression, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TTarget :  class { }
-        public ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
+        public ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
-        public ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(TViewModel viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
+        public ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(TViewModel? viewModel, TView view, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
     }
@@ -456,33 +456,33 @@ namespace ReactiveUI
         [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
                 "view",
                 "isViewModel"})]
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
         [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
                 "view",
                 "isViewModel"})]
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
         [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
                 "view",
                 "isViewModel"})]
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, System.Func<TVMProp, TVProp> vmToViewConverter, System.Func<TVProp, TVMProp> viewToVmConverter)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
-        [return: System.Runtime.CompilerServices.TupleElementNames(new string[] {
+        [return: System.Runtime.CompilerServices.TupleElementNames(new string?[]?[] {
                 "view",
                 "isViewModel"})]
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, System.ValueTuple<object?, bool>>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, System.IObservable<TDontCare>? signalViewUpdate, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null, ReactiveUI.IBindingTypeConverter? viewToVMConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
         public static System.IDisposable BindTo<TValue, TTarget, TTValue>(this System.IObservable<TValue> @this, TTarget target, System.Linq.Expressions.Expression<System.Func<TTarget, TTValue>> property, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TTarget :  class { }
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TOut>> viewProperty, System.Func<TProp, TOut> selector)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
-        public static ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
+        public static ReactiveUI.IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(this TView view, TViewModel? viewModel, System.Linq.Expressions.Expression<System.Func<TViewModel, TVMProp>> vmProperty, System.Linq.Expressions.Expression<System.Func<TView, TVProp>> viewProperty, object? conversionHint = null, ReactiveUI.IBindingTypeConverter? vmToViewConverterOverride = null)
             where TViewModel :  class
             where TView :  class, ReactiveUI.IViewFor { }
     }
diff --git a/src/ReactiveUI.Tests/Platforms/winforms/API/ApiApprovalTests.Winforms.net472.approved.txt b/src/ReactiveUI.Tests/Platforms/winforms/API/ApiApprovalTests.Winforms.net472.approved.txt
index b1babfa47d..56dc8107c9 100644
--- a/src/ReactiveUI.Tests/Platforms/winforms/API/ApiApprovalTests.Winforms.net472.approved.txt
+++ b/src/ReactiveUI.Tests/Platforms/winforms/API/ApiApprovalTests.Winforms.net472.approved.txt
@@ -10,7 +10,7 @@ namespace ReactiveUI.Winforms
     public class ContentControlBindingHook : ReactiveUI.IPropertyBindingHook
     {
         public ContentControlBindingHook() { }
-        public bool ExecuteHook(object source, object target, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewModelProperties, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewProperties, ReactiveUI.BindingDirection direction) { }
+        public bool ExecuteHook(object? source, object target, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewModelProperties, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewProperties, ReactiveUI.BindingDirection direction) { }
     }
     public class CreatesWinformsCommandBinding : ReactiveUI.ICreatesCommandBinding
     {
diff --git a/src/ReactiveUI.Tests/Platforms/winforms/API/ApiApprovalTests.Winforms.netcoreapp3.1.approved.txt b/src/ReactiveUI.Tests/Platforms/winforms/API/ApiApprovalTests.Winforms.netcoreapp3.1.approved.txt
index 9cbbe61b09..657513e73c 100644
--- a/src/ReactiveUI.Tests/Platforms/winforms/API/ApiApprovalTests.Winforms.netcoreapp3.1.approved.txt
+++ b/src/ReactiveUI.Tests/Platforms/winforms/API/ApiApprovalTests.Winforms.netcoreapp3.1.approved.txt
@@ -10,7 +10,7 @@ namespace ReactiveUI.Winforms
     public class ContentControlBindingHook : ReactiveUI.IPropertyBindingHook
     {
         public ContentControlBindingHook() { }
-        public bool ExecuteHook(object source, object target, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewModelProperties, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewProperties, ReactiveUI.BindingDirection direction) { }
+        public bool ExecuteHook(object? source, object target, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewModelProperties, System.Func<ReactiveUI.IObservedChange<, >[]> getCurrentViewProperties, ReactiveUI.BindingDirection direction) { }
     }
     public class CreatesWinformsCommandBinding : ReactiveUI.ICreatesCommandBinding
     {
diff --git a/src/ReactiveUI.Winforms/ContentControlBindingHook.cs b/src/ReactiveUI.Winforms/ContentControlBindingHook.cs
index a908523aff..d889bde808 100644
--- a/src/ReactiveUI.Winforms/ContentControlBindingHook.cs
+++ b/src/ReactiveUI.Winforms/ContentControlBindingHook.cs
@@ -17,7 +17,7 @@ namespace ReactiveUI.Winforms
     public class ContentControlBindingHook : IPropertyBindingHook
     {
         /// <inheritdoc/>
-        public bool ExecuteHook(object source, object target, Func<IObservedChange<object, object>[]> getCurrentViewModelProperties, Func<IObservedChange<object, object>[]> getCurrentViewProperties, BindingDirection direction)
+        public bool ExecuteHook(object? source, object target, Func<IObservedChange<object, object>[]> getCurrentViewModelProperties, Func<IObservedChange<object, object>[]> getCurrentViewProperties, BindingDirection direction)
         {
             if (getCurrentViewProperties == null)
             {
diff --git a/src/ReactiveUI/Bindings/Property/IPropertyBinderImplementation.cs b/src/ReactiveUI/Bindings/Property/IPropertyBinderImplementation.cs
index 826f56ef16..dc68f54362 100644
--- a/src/ReactiveUI/Bindings/Property/IPropertyBinderImplementation.cs
+++ b/src/ReactiveUI/Bindings/Property/IPropertyBinderImplementation.cs
@@ -65,7 +65,7 @@ public interface IPropertyBinderImplementation : IEnableLogger
         /// disconnects the binding.
         /// </returns>
         IReactiveBinding<TView, TViewModel, (object? view, bool isViewModel)>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(
-                TViewModel viewModel,
+                TViewModel? viewModel,
                 TView view,
                 Expression<Func<TViewModel, TVMProp>> vmProperty,
                 Expression<Func<TView, TVProp>> viewProperty,
@@ -122,7 +122,7 @@ public interface IPropertyBinderImplementation : IEnableLogger
         /// disconnects the binding.
         /// </returns>
         IReactiveBinding<TView, TViewModel, (object? view, bool isViewModel)>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(
-                TViewModel viewModel,
+                TViewModel? viewModel,
                 TView view,
                 Expression<Func<TViewModel, TVMProp>> vmProperty,
                 Expression<Func<TView, TVProp>> viewProperty,
@@ -172,7 +172,7 @@ public interface IPropertyBinderImplementation : IEnableLogger
         /// There is no registered converter from <typeparamref name="TVMProp"/> to <typeparamref name="TVProp"/>.
         /// </exception>
         IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(
-                TViewModel viewModel,
+                TViewModel? viewModel,
                 TView view,
                 Expression<Func<TViewModel, TVMProp>> vmProperty,
                 Expression<Func<TView, TVProp>> viewProperty,
@@ -213,7 +213,7 @@ public interface IPropertyBinderImplementation : IEnableLogger
         /// disconnects the binding.
         /// </returns>
         IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(
-            TViewModel viewModel,
+            TViewModel? viewModel,
             TView view,
             Expression<Func<TViewModel, TProp>> vmProperty,
             Expression<Func<TView, TOut>> viewProperty,
diff --git a/src/ReactiveUI/Bindings/Property/PropertyBinderImplementation.cs b/src/ReactiveUI/Bindings/Property/PropertyBinderImplementation.cs
index 6cce6402cf..2c8b0b0430 100644
--- a/src/ReactiveUI/Bindings/Property/PropertyBinderImplementation.cs
+++ b/src/ReactiveUI/Bindings/Property/PropertyBinderImplementation.cs
@@ -1,4 +1,4 @@
-// Copyright (c) 2019 .NET Foundation and Contributors. All rights reserved.
+// Copyright (c) 2019 .NET Foundation and Contributors. All rights reserved.
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for full license information.
@@ -48,7 +48,7 @@ public class PropertyBinderImplementation : IPropertyBinderImplementation
 
         /// <inheritdoc />
         public IReactiveBinding<TView, TViewModel, (object? view, bool isViewModel)> Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(
-                TViewModel viewModel,
+                TViewModel? viewModel,
                 TView view,
                 Expression<Func<TViewModel, TVMProp>> vmProperty,
                 Expression<Func<TView, TVProp>> viewProperty,
@@ -95,7 +95,7 @@ bool ViewToVmFunc(TVProp vValue, out TVMProp vmValue)
 
         /// <inheritdoc />
         public IReactiveBinding<TView, TViewModel, (object? view, bool isViewModel)>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(
-                TViewModel viewModel,
+                TViewModel? viewModel,
                 TView view,
                 Expression<Func<TViewModel, TVMProp>> vmProperty,
                 Expression<Func<TView, TVProp>> viewProperty,
@@ -142,7 +142,7 @@ bool ViewToVmFunc(TVProp vValue, out TVMProp vmValue)
 
         /// <inheritdoc />
         public IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(
-                TViewModel viewModel,
+                TViewModel? viewModel,
                 TView view,
                 Expression<Func<TViewModel, TVMProp>> vmProperty,
                 Expression<Func<TView, TVProp>> viewProperty,
@@ -195,7 +195,7 @@ bool ViewToVmFunc(TVProp vValue, out TVMProp vmValue)
 
         /// <inheritdoc />
         public IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(
-            TViewModel viewModel,
+            TViewModel? viewModel,
             TView view,
             Expression<Func<TViewModel, TProp>> vmProperty,
             Expression<Func<TView, TOut>> viewProperty,
@@ -357,7 +357,7 @@ public IDisposable BindTo<TValue, TTarget, TTValue>(
             return (setObservable.Subscribe(_ => { }, ex => this.Log().Error(ex, $"{viewExpression} Binding received an Exception!")), setObservable);
         }
 
-        private bool EvalBindingHooks<TViewModel, TView>(TViewModel viewModel, TView view, Expression vmExpression, Expression viewExpression, BindingDirection direction)
+        private bool EvalBindingHooks<TViewModel, TView>(TViewModel? viewModel, TView view, Expression vmExpression, Expression viewExpression, BindingDirection direction)
             where TViewModel : class
         {
             var hooks = Locator.Current.GetServices<IPropertyBindingHook>();
@@ -380,7 +380,7 @@ private bool EvalBindingHooks<TViewModel, TView>(TViewModel viewModel, TView vie
             {
                 vmFetcher = () => new IObservedChange<object, object?>[]
                 {
-                    new ObservedChange<object, object>(null!, null!, viewModel)
+                    new ObservedChange<object, object?>(null!, null!, viewModel)
                 };
             }
 
@@ -404,7 +404,7 @@ private bool EvalBindingHooks<TViewModel, TView>(TViewModel viewModel, TView vie
         }
 
         private IReactiveBinding<TView, TViewModel, (object? view, bool isViewModel)> BindImpl<TViewModel, TView, TVMProp, TVProp, TDontCare>(
-            TViewModel viewModel,
+            TViewModel? viewModel,
             TView view,
             Expression<Func<TViewModel, TVMProp>> vmProperty,
             Expression<Func<TView, TVProp>> viewProperty,
diff --git a/src/ReactiveUI/Bindings/Property/PropertyBindingMixins.cs b/src/ReactiveUI/Bindings/Property/PropertyBindingMixins.cs
index 2f1b7bcd58..2ce6b390a0 100644
--- a/src/ReactiveUI/Bindings/Property/PropertyBindingMixins.cs
+++ b/src/ReactiveUI/Bindings/Property/PropertyBindingMixins.cs
@@ -59,7 +59,7 @@ static PropertyBindingMixins()
         /// </returns>
         public static IReactiveBinding<TView, TViewModel, (object? view, bool isViewModel)>? Bind<TViewModel, TView, TVMProp, TVProp>(
                 this TView view,
-                TViewModel viewModel,
+                TViewModel? viewModel,
                 Expression<Func<TViewModel, TVMProp>> vmProperty,
                 Expression<Func<TView, TVProp>> viewProperty,
                 object? conversionHint = null,
@@ -126,7 +126,7 @@ static PropertyBindingMixins()
         /// </returns>
         public static IReactiveBinding<TView, TViewModel, (object? view, bool isViewModel)>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(
                 this TView view,
-                TViewModel viewModel,
+                TViewModel? viewModel,
                 Expression<Func<TViewModel, TVMProp>> vmProperty,
                 Expression<Func<TView, TVProp>> viewProperty,
                 IObservable<TDontCare>? signalViewUpdate,
@@ -170,7 +170,7 @@ static PropertyBindingMixins()
         /// </returns>
         public static IReactiveBinding<TView, TViewModel, (object? view, bool isViewModel)>? Bind<TViewModel, TView, TVMProp, TVProp>(
             this TView view,
-            TViewModel viewModel,
+            TViewModel? viewModel,
             Expression<Func<TViewModel, TVMProp>> vmProperty,
             Expression<Func<TView, TVProp>> viewProperty,
             Func<TVMProp, TVProp> vmToViewConverter,
@@ -220,7 +220,7 @@ static PropertyBindingMixins()
         /// </returns>
         public static IReactiveBinding<TView, TViewModel, (object? view, bool isViewModel)>? Bind<TViewModel, TView, TVMProp, TVProp, TDontCare>(
             this TView view,
-            TViewModel viewModel,
+            TViewModel? viewModel,
             Expression<Func<TViewModel, TVMProp>> vmProperty,
             Expression<Func<TView, TVProp>> viewProperty,
             IObservable<TDontCare>? signalViewUpdate,
@@ -270,7 +270,7 @@ static PropertyBindingMixins()
         /// </returns>
         public static IReactiveBinding<TView, TViewModel, TVProp>? OneWayBind<TViewModel, TView, TVMProp, TVProp>(
                 this TView view,
-                TViewModel viewModel,
+                TViewModel? viewModel,
                 Expression<Func<TViewModel, TVMProp>> vmProperty,
                 Expression<Func<TView, TVProp>> viewProperty,
                 object? conversionHint = null,
@@ -319,7 +319,7 @@ static PropertyBindingMixins()
         /// </returns>
         public static IReactiveBinding<TView, TViewModel, TOut>? OneWayBind<TViewModel, TView, TProp, TOut>(
                 this TView view,
-                TViewModel viewModel,
+                TViewModel? viewModel,
                 Expression<Func<TViewModel, TProp>> vmProperty,
                 Expression<Func<TView, TOut>> viewProperty,
                 Func<TProp, TOut> selector)
diff --git a/src/ReactiveUI/Bindings/Reactive/IReactiveBinding.cs b/src/ReactiveUI/Bindings/Reactive/IReactiveBinding.cs
index b856a5ea54..bf5c9bcd7e 100644
--- a/src/ReactiveUI/Bindings/Reactive/IReactiveBinding.cs
+++ b/src/ReactiveUI/Bindings/Reactive/IReactiveBinding.cs
@@ -24,7 +24,7 @@ public interface IReactiveBinding<out TView, out TViewModel, out TValue> : IDisp
         /// <summary>
         /// Gets the instance of the view model this binding is applied to.
         /// </summary>
-        TViewModel ViewModel { get; }
+        TViewModel? ViewModel { get; }
 
         /// <summary>
         /// Gets an expression representing the propertyon the viewmodel bound to the view.
diff --git a/src/ReactiveUI/Bindings/Reactive/ReactiveBinding.cs b/src/ReactiveUI/Bindings/Reactive/ReactiveBinding.cs
index 61ec5f5235..6daee7cad3 100644
--- a/src/ReactiveUI/Bindings/Reactive/ReactiveBinding.cs
+++ b/src/ReactiveUI/Bindings/Reactive/ReactiveBinding.cs
@@ -16,7 +16,7 @@ internal class ReactiveBinding<TView, TViewModel, TValue> : IReactiveBinding<TVi
 
         public ReactiveBinding(
             TView view,
-            TViewModel viewModel,
+            TViewModel? viewModel,
             Expression viewExpression,
             Expression viewModelExpression,
             IObservable<TValue> changed,
@@ -34,7 +34,7 @@ public ReactiveBinding(
         }
 
         /// <inheritdoc />
-        public TViewModel ViewModel { get; }
+        public TViewModel? ViewModel { get; }
 
         /// <inheritdoc />
         public Expression ViewModelExpression { get; }
diff --git a/src/ReactiveUI/Expression/Reflection.cs b/src/ReactiveUI/Expression/Reflection.cs
index 63523cdcd0..6d91abba94 100644
--- a/src/ReactiveUI/Expression/Reflection.cs
+++ b/src/ReactiveUI/Expression/Reflection.cs
@@ -435,7 +435,7 @@ public static bool IsStatic(this PropertyInfo item)
         }
 
         [SuppressMessage("Microsoft.Performance", "CA1801", Justification = "TViewModel used to help generic calling.")]
-        internal static IObservable<object> ViewModelWhenAnyValue<TView, TViewModel>(TViewModel viewModel, TView view, Expression expression)
+        internal static IObservable<object> ViewModelWhenAnyValue<TView, TViewModel>(TViewModel? viewModel, TView view, Expression expression)
             where TView : class, IViewFor
             where TViewModel : class
         {
diff --git a/src/ReactiveUI/Interfaces/IPropertyBindingHook.cs b/src/ReactiveUI/Interfaces/IPropertyBindingHook.cs
index 65c1df7398..be2a9126e2 100644
--- a/src/ReactiveUI/Interfaces/IPropertyBindingHook.cs
+++ b/src/ReactiveUI/Interfaces/IPropertyBindingHook.cs
@@ -23,7 +23,7 @@ public interface IPropertyBindingHook
         /// <param name="getCurrentViewProperties">Get current view properties.</param>
         /// <param name="direction">The Binding direction.</param>
         bool ExecuteHook(
-            object source,
+            object? source,
             object target,
             Func<IObservedChange<object, object>[]> getCurrentViewModelProperties,
             Func<IObservedChange<object, object>[]> getCurrentViewProperties,
diff --git a/src/ReactiveUI/Platforms/windows-common/AutoDataTemplateBindingHook.cs b/src/ReactiveUI/Platforms/windows-common/AutoDataTemplateBindingHook.cs
index 124d44fdb9..1a220af880 100644
--- a/src/ReactiveUI/Platforms/windows-common/AutoDataTemplateBindingHook.cs
+++ b/src/ReactiveUI/Platforms/windows-common/AutoDataTemplateBindingHook.cs
@@ -56,7 +56,7 @@ public class AutoDataTemplateBindingHook : IPropertyBindingHook
         });
 
         /// <inheritdoc/>
-        public bool ExecuteHook(object source, object target, Func<IObservedChange<object, object>[]> getCurrentViewModelProperties, Func<IObservedChange<object, object>[]> getCurrentViewProperties, BindingDirection direction)
+        public bool ExecuteHook(object? source, object target, Func<IObservedChange<object, object>[]> getCurrentViewModelProperties, Func<IObservedChange<object, object>[]> getCurrentViewProperties, BindingDirection direction)
         {
             if (getCurrentViewProperties == null)
             {