diff --git a/Revit.Async.Shared/RevitTask.cs b/Revit.Async.Shared/RevitTask.cs
index 3b1b90a..fa5e7ce 100644
--- a/Revit.Async.Shared/RevitTask.cs
+++ b/Revit.Async.Shared/RevitTask.cs
@@ -87,7 +87,7 @@ public Task<TResult> Raise<THandler, TParameter, TResult>(TParameter parameter)
         /// <inheritdoc />
         public void Register<TParameter, TResult>(IGenericExternalEventHandler<TParameter, TResult> handler)
         {
-            ScopedRegisteredExternalEvents.TryAdd(handler.GetType(), new ExternalEventPair(handler));
+            ScopedRegisteredExternalEvents.TryAdd(handler.GetType(), new ExternalEventPair(handler, () => CreateExternalEvent(handler)));
         }
 
         #endregion