diff --git a/src/Cashier/NCafe.Cashier.Api/Projections/ProductCreated.cs b/src/Cashier/NCafe.Cashier.Api/Projections/ProductCreated.cs
index 45c9b59..49f1f96 100644
--- a/src/Cashier/NCafe.Cashier.Api/Projections/ProductCreated.cs
+++ b/src/Cashier/NCafe.Cashier.Api/Projections/ProductCreated.cs
@@ -2,9 +2,8 @@
 
 namespace NCafe.Cashier.Api.Projections;
 
-public record ProductCreated : IEvent
+public record ProductCreated : Event
 {
-    public Guid Id { get; init; }
     public string Name { get; init; }
     public decimal Price { get; init; }
 }
diff --git a/src/Common/NCafe.Core/Domain/AggregateRoot.cs b/src/Common/NCafe.Core/Domain/AggregateRoot.cs
index ceb42e0..cee07d2 100644
--- a/src/Common/NCafe.Core/Domain/AggregateRoot.cs
+++ b/src/Common/NCafe.Core/Domain/AggregateRoot.cs
@@ -6,22 +6,22 @@ namespace NCafe.Core.Domain;
 public abstract class AggregateRoot
 {
     public Guid Id { get; protected set; }
-    public long Version { get; protected set; } = -1;
+    internal long Version { get; set; } = -1;
 
-    private readonly List<IEvent> _pendingEvents = [];
+    private readonly List<Event> _pendingEvents = [];
 
     protected void RaiseEvent(Event @event)
     {
-        @event.Version = Version + 1;
+        ((IEvent)@event).Version = Version + 1;
 
         ApplyEvent(@event);
 
         _pendingEvents.Add(@event);
     }
 
-    public IEnumerable<IEvent> GetPendingEvents()
+    public IReadOnlyCollection<Event> GetPendingEvents()
     {
-        return [.. _pendingEvents];
+        return _pendingEvents.AsReadOnly();
     }
 
     internal void ClearPendingEvents()
@@ -31,7 +31,7 @@ internal void ClearPendingEvents()
 
     internal void ApplyEvent(Event @event)
     {
-        if (@event.Version != Version + 1)
+        if (((IEvent)@event).Version != Version + 1)
         {
             throw new InvalidVersionException(@event, this);
         }
diff --git a/src/Common/NCafe.Core/Domain/Event.cs b/src/Common/NCafe.Core/Domain/Event.cs
index 618a7b4..3e4bb08 100644
--- a/src/Common/NCafe.Core/Domain/Event.cs
+++ b/src/Common/NCafe.Core/Domain/Event.cs
@@ -7,5 +7,5 @@ public abstract record Event : IEvent
     public Guid Id { get; init; }
 
     [JsonInclude]
-    public long Version { get; internal protected set; }
+    long IEvent.Version { get; set; }
 }
diff --git a/src/Common/NCafe.Core/Domain/IEvent.cs b/src/Common/NCafe.Core/Domain/IEvent.cs
index 84c950b..d622656 100644
--- a/src/Common/NCafe.Core/Domain/IEvent.cs
+++ b/src/Common/NCafe.Core/Domain/IEvent.cs
@@ -1,6 +1,6 @@
 namespace NCafe.Core.Domain;
 
-public interface IEvent
+internal interface IEvent
 {
-    Guid Id { get; }
+    long Version { get; internal protected set; }
 }
diff --git a/src/Common/NCafe.Core/Exceptions/InvalidVersionException.cs b/src/Common/NCafe.Core/Exceptions/InvalidVersionException.cs
index 0f57b61..8300eed 100644
--- a/src/Common/NCafe.Core/Exceptions/InvalidVersionException.cs
+++ b/src/Common/NCafe.Core/Exceptions/InvalidVersionException.cs
@@ -3,6 +3,6 @@
 namespace NCafe.Core.Exceptions;
 
 public class InvalidVersionException(Event @event, AggregateRoot aggregateRoot)
-    : DomainException($"{@event.GetType().Name} Event v{@event.Version} cannot be applied to Aggregate {aggregateRoot.GetType().Name} : {aggregateRoot.Id} v{aggregateRoot.Version}")
+    : DomainException($"{@event.GetType().Name} Event v{((IEvent)@event).Version} cannot be applied to Aggregate {aggregateRoot.GetType().Name} : {aggregateRoot.Id} v{aggregateRoot.Version}")
 {
 }
diff --git a/src/Common/NCafe.Core/Projections/IProjectionService.cs b/src/Common/NCafe.Core/Projections/IProjectionService.cs
index db0868b..f00e3c5 100644
--- a/src/Common/NCafe.Core/Projections/IProjectionService.cs
+++ b/src/Common/NCafe.Core/Projections/IProjectionService.cs
@@ -3,12 +3,12 @@
 
 namespace NCafe.Core.Projections;
 
-public delegate Guid GetModelId<in TEvent>(TEvent @event) where TEvent : class, IEvent;
-public delegate void ModelUpdate<in TEvent, T>(TEvent @event, T model) where TEvent : class, IEvent;
+public delegate Guid GetModelId<in TEvent>(TEvent @event) where TEvent : Event;
+public delegate void ModelUpdate<in TEvent, T>(TEvent @event, T model) where TEvent : Event;
 
 public interface IProjectionService<T> where T : ReadModel
 {
     Task Start(CancellationToken cancellationToken);
-    void OnCreate<TEvent>(Func<TEvent, T> handler) where TEvent : class, IEvent;
-    void OnUpdate<TEvent>(GetModelId<TEvent> getId, ModelUpdate<TEvent, T> update) where TEvent : class, IEvent;
+    void OnCreate<TEvent>(Func<TEvent, T> handler) where TEvent : Event;
+    void OnUpdate<TEvent>(GetModelId<TEvent> getId, ModelUpdate<TEvent, T> update) where TEvent : Event;
 }
diff --git a/src/Common/NCafe.Infrastructure/EventStore/EventStoreProjectionService.cs b/src/Common/NCafe.Infrastructure/EventStore/EventStoreProjectionService.cs
index 845b0f5..4be0148 100644
--- a/src/Common/NCafe.Infrastructure/EventStore/EventStoreProjectionService.cs
+++ b/src/Common/NCafe.Infrastructure/EventStore/EventStoreProjectionService.cs
@@ -54,7 +54,7 @@ private void SubscriptionDropped(StreamSubscription subscription, SubscriptionDr
         _logger.LogError("Subscription Dropped.");
     }
 
-    public void OnCreate<TEvent>(Func<TEvent, T> handler) where TEvent : class, IEvent
+    public void OnCreate<TEvent>(Func<TEvent, T> handler) where TEvent : Event
     {
         MapEventHandler<TEvent>(resolvedEvent =>
         {
@@ -67,7 +67,7 @@ public void OnCreate<TEvent>(Func<TEvent, T> handler) where TEvent : class, IEve
         });
     }
 
-    public void OnUpdate<TEvent>(GetModelId<TEvent> getId, ModelUpdate<TEvent, T> update) where TEvent : class, IEvent
+    public void OnUpdate<TEvent>(GetModelId<TEvent> getId, ModelUpdate<TEvent, T> update) where TEvent : Event
     {
         MapEventHandler<TEvent>(resolvedEvent =>
         {
diff --git a/src/Common/NCafe.Infrastructure/EventStore/EventStoreRepository.cs b/src/Common/NCafe.Infrastructure/EventStore/EventStoreRepository.cs
index fc13dfe..8d487f6 100644
--- a/src/Common/NCafe.Infrastructure/EventStore/EventStoreRepository.cs
+++ b/src/Common/NCafe.Infrastructure/EventStore/EventStoreRepository.cs
@@ -47,8 +47,7 @@ public async Task Save(AggregateRoot aggregate)
         var streamName = ToStreamName(aggregate.Id, aggregate.GetType());
         var pendingEvents = aggregate.GetPendingEvents().ToArray();
 
-        var originalVersion = aggregate.Version - pendingEvents.Length;
-        var expectedVersion = originalVersion;
+        var expectedVersion = aggregate.Version - pendingEvents.Length;
 
         var eventsToAppend = pendingEvents
             .Select(e => e.AsEventData())