diff --git a/LightweightIocContainer/Interfaces/Registrations/Fluent/IOnCreate.cs b/LightweightIocContainer/Interfaces/Registrations/Fluent/IOnCreate.cs
index ed728d3..a53bf15 100644
--- a/LightweightIocContainer/Interfaces/Registrations/Fluent/IOnCreate.cs
+++ b/LightweightIocContainer/Interfaces/Registrations/Fluent/IOnCreate.cs
@@ -15,8 +15,8 @@ public interface IOnCreate
     /// This <see cref="Action"/> is invoked when an instance of this type is created.
     /// <para>Can be set in the <see cref="IIocInstaller"/> by calling <see cref="IOnCreate{TInterface, TImplementation}.OnCreate"/></para>
     /// </summary>
-    internal Action<object?>? OnCreateAction { get; }
-    internal Func<object?, Task>? OnCreateActionAsync { get; }
+    internal Action<object>? OnCreateAction { get; }
+    internal Func<object, Task>? OnCreateActionAsync { get; }
 }
 
 /// <summary>
@@ -31,7 +31,12 @@ public interface IOnCreate<TInterface, TImplementation> : IOnCreate where TImple
     /// </summary>
     /// <param name="action">The <see cref="Action{T}"/></param>
     /// <returns>The current instance of this <see cref="ITypedRegistration{TInterface,TImplementation}"/></returns>
-    ITypedRegistration<TInterface, TImplementation> OnCreate(Action<TImplementation?> action);
+    ITypedRegistration<TInterface, TImplementation> OnCreate(Action<TImplementation> action);
     
-    ITypedRegistration<TInterface, TImplementation> OnCreateAsync(Func<TImplementation?, Task> action);
+    /// <summary>
+    /// Pass an <see cref="Action{T}"/> that will be invoked when an instance of this type is created
+    /// </summary>
+    /// <param name="action">The <see cref="Action{T}"/></param>
+    /// <returns>The current instance of this <see cref="ITypedRegistration{TInterface,TImplementation}"/></returns>
+    ITypedRegistration<TInterface, TImplementation> OnCreateAsync(Func<TImplementation, Task> action);
 }
\ No newline at end of file
diff --git a/LightweightIocContainer/IocContainer.cs b/LightweightIocContainer/IocContainer.cs
index b3a53ed..9a87c67 100644
--- a/LightweightIocContainer/IocContainer.cs
+++ b/LightweightIocContainer/IocContainer.cs
@@ -398,7 +398,7 @@ public class IocContainer : IIocContainer, IIocResolver
         if (registration is ILifestyleProvider { Lifestyle: Lifestyle.Singleton }) 
             _singletons.Add((GetType<T>(registration), instance));
 
-        if (registration is IOnCreate onCreateRegistration)
+        if (registration is IOnCreate onCreateRegistration && instance is not null)
             onCreateRegistration.OnCreateAction?.Invoke(instance);
 
         return instance;
@@ -407,7 +407,7 @@ public class IocContainer : IIocContainer, IIocResolver
     private async Task<T> CreateInstanceAsync<T>(IRegistration registration, object?[]? arguments)
     {
         T instance = CreateInstance<T>(registration, arguments);
-        if (registration is IOnCreate { OnCreateActionAsync: not null } onCreateRegistration)
+        if (registration is IOnCreate { OnCreateActionAsync: not null } onCreateRegistration && instance is not null)
             await onCreateRegistration.OnCreateActionAsync.Invoke(instance);
 
         return instance;
diff --git a/LightweightIocContainer/LightweightIocContainer.xml b/LightweightIocContainer/LightweightIocContainer.xml
index c90c1b9..32746d5 100644
--- a/LightweightIocContainer/LightweightIocContainer.xml
+++ b/LightweightIocContainer/LightweightIocContainer.xml
@@ -620,6 +620,13 @@
             <param name="action">The <see cref="T:System.Action`1"/></param>
             <returns>The current instance of this <see cref="T:LightweightIocContainer.Interfaces.Registrations.ITypedRegistration`2"/></returns>
         </member>
+        <member name="M:LightweightIocContainer.Interfaces.Registrations.Fluent.IOnCreate`2.OnCreateAsync(System.Func{`1,System.Threading.Tasks.Task})">
+            <summary>
+            Pass an <see cref="T:System.Action`1"/> that will be invoked when an instance of this type is created
+            </summary>
+            <param name="action">The <see cref="T:System.Action`1"/></param>
+            <returns>The current instance of this <see cref="T:LightweightIocContainer.Interfaces.Registrations.ITypedRegistration`2"/></returns>
+        </member>
         <member name="T:LightweightIocContainer.Interfaces.Registrations.Fluent.IWithDisposeStrategy">
             <summary>
             Provides a <see cref="T:LightweightIocContainer.DisposeStrategy"/> to an <see cref="T:LightweightIocContainer.Interfaces.Registrations.IRegistration"/>
diff --git a/LightweightIocContainer/Registrations/MultipleMultitonRegistration.cs b/LightweightIocContainer/Registrations/MultipleMultitonRegistration.cs
index 4d2ddbd..3afe7d4 100644
--- a/LightweightIocContainer/Registrations/MultipleMultitonRegistration.cs
+++ b/LightweightIocContainer/Registrations/MultipleMultitonRegistration.cs
@@ -43,7 +43,7 @@ internal class MultipleMultitonRegistration<TInterface1, TInterface2, TImplement
     /// </summary>
     /// <param name="action">The <see cref="Action{T}"/></param>
     /// <returns>The current instance of this <see cref="ITypedRegistration{TInterface,TImplementation}"/></returns>
-    public override ITypedRegistration<TInterface1, TImplementation> OnCreate(Action<TImplementation?> action)
+    public override ITypedRegistration<TInterface1, TImplementation> OnCreate(Action<TImplementation> action)
     {
         foreach (IRegistration registration in Registrations)
         {
diff --git a/LightweightIocContainer/Registrations/MultipleRegistration.cs b/LightweightIocContainer/Registrations/MultipleRegistration.cs
index 1ad8948..c957f75 100644
--- a/LightweightIocContainer/Registrations/MultipleRegistration.cs
+++ b/LightweightIocContainer/Registrations/MultipleRegistration.cs
@@ -62,7 +62,7 @@ internal class MultipleRegistration<TInterface1, TInterface2, TImplementation> :
     /// </summary>
     /// <param name="action">The <see cref="Action{T}"/></param>
     /// <returns>The current instance of this <see cref="ITypedRegistration{TInterface,TImplementation}"/></returns>
-    public override ITypedRegistration<TInterface1, TImplementation> OnCreate(Action<TImplementation?> action)
+    public override ITypedRegistration<TInterface1, TImplementation> OnCreate(Action<TImplementation> action)
     {
         foreach (IRegistration registration in Registrations)
         {
@@ -110,7 +110,7 @@ internal class MultipleRegistration<TInterface1, TInterface2, TInterface3, TImpl
     /// </summary>
     /// <param name="action">The <see cref="Action{T}"/></param>
     /// <returns>The current instance of this <see cref="ITypedRegistration{TInterface,TImplementation}"/></returns>
-    public override ITypedRegistration<TInterface1, TImplementation> OnCreate(Action<TImplementation?> action)
+    public override ITypedRegistration<TInterface1, TImplementation> OnCreate(Action<TImplementation> action)
     {
         foreach (IRegistration registration in Registrations)
         {
@@ -163,7 +163,7 @@ internal class MultipleRegistration<TInterface1, TInterface2, TInterface3, TInte
     /// </summary>
     /// <param name="action">The <see cref="Action{T}"/></param>
     /// <returns>The current instance of this <see cref="ITypedRegistration{TInterface,TImplementation}"/></returns>
-    public override ITypedRegistration<TInterface1, TImplementation> OnCreate(Action<TImplementation?> action)
+    public override ITypedRegistration<TInterface1, TImplementation> OnCreate(Action<TImplementation> action)
     {
         foreach (IRegistration registration in Registrations)
         {
@@ -221,7 +221,7 @@ internal class MultipleRegistration<TInterface1, TInterface2, TInterface3, TInte
     /// </summary>
     /// <param name="action">The <see cref="Action{T}"/></param>
     /// <returns>The current instance of this <see cref="ITypedRegistration{TInterface,TImplementation}"/></returns>
-    public override ITypedRegistration<TInterface1, TImplementation> OnCreate(Action<TImplementation?> action)
+    public override ITypedRegistration<TInterface1, TImplementation> OnCreate(Action<TImplementation> action)
     {
         foreach (IRegistration registration in Registrations)
         {
diff --git a/LightweightIocContainer/Registrations/TypedRegistration.cs b/LightweightIocContainer/Registrations/TypedRegistration.cs
index ae5f32a..b5652bc 100644
--- a/LightweightIocContainer/Registrations/TypedRegistration.cs
+++ b/LightweightIocContainer/Registrations/TypedRegistration.cs
@@ -34,40 +34,40 @@ internal class TypedRegistration<TInterface, TImplementation> : RegistrationBase
     /// This <see cref="Action"/> is invoked when an instance of this type is created.
     /// <para>Can be set in the <see cref="IIocInstaller"/> by calling <see cref="IOnCreate{TInterface,TImplementation}.OnCreate"/></para>
     /// </summary>
-    private Action<object?>? OnCreateAction { get; set; }
+    private Action<object>? OnCreateAction { get; set; }
 
     /// <summary>
     /// This <see cref="Action"/> is invoked when an instance of this type is created.
     /// <para>Can be set in the <see cref="IIocInstaller"/> by calling <see cref="IOnCreate{TInterface,TImplementation}.OnCreate"/></para>
     /// </summary>
-    private Func<object?, Task>? OnCreateActionAsync { get; set; }
+    private Func<object, Task>? OnCreateActionAsync { get; set; }
 
     /// <summary>
     /// This <see cref="Action"/> is invoked when an instance of this type is created.
     /// <para>Can be set in the <see cref="IIocInstaller"/> by calling <see cref="IOnCreate{TInterface,TImplementation}.OnCreate"/></para>
     /// </summary>
-    Action<object?>? IOnCreate.OnCreateAction => OnCreateAction;
+    Action<object>? IOnCreate.OnCreateAction => OnCreateAction;
     
     /// <summary>
     /// This <see cref="Action"/> is invoked when an instance of this type is created.
     /// <para>Can be set in the <see cref="IIocInstaller"/> by calling <see cref="IOnCreate{TInterface,TImplementation}.OnCreate"/></para>
     /// </summary>
-    Func<object?, Task>? IOnCreate.OnCreateActionAsync => OnCreateActionAsync;
+    Func<object, Task>? IOnCreate.OnCreateActionAsync => OnCreateActionAsync;
 
     /// <summary>
     /// Pass an <see cref="Action{T}"/> that will be invoked when an instance of this type is created
     /// </summary>
     /// <param name="action">The <see cref="Action{T}"/></param>
     /// <returns>The current instance of this <see cref="ITypedRegistration{TInterface,TImplementation}"/></returns>
-    public virtual ITypedRegistration<TInterface, TImplementation> OnCreate(Action<TImplementation?> action)
+    public virtual ITypedRegistration<TInterface, TImplementation> OnCreate(Action<TImplementation> action)
     {
-        OnCreateAction = a => action((TImplementation?) a);
+        OnCreateAction = a => action((TImplementation) a);
         return this;
     }
 
-    public ITypedRegistration<TInterface, TImplementation> OnCreateAsync(Func<TImplementation?, Task> action)
+    public ITypedRegistration<TInterface, TImplementation> OnCreateAsync(Func<TImplementation, Task> action)
     {
-        OnCreateActionAsync = a => action((TImplementation?) a);
+        OnCreateActionAsync = a => action((TImplementation) a);
         return this;
     }