diff --git a/RhSolutions.AddIn/AddIn/RhSolutionsAddIn.cs b/RhSolutions.AddIn/AddIn/RhSolutionsAddIn.cs
index 19ae437..58002ee 100644
--- a/RhSolutions.AddIn/AddIn/RhSolutionsAddIn.cs
+++ b/RhSolutions.AddIn/AddIn/RhSolutionsAddIn.cs
@@ -8,7 +8,7 @@ using System.Net;
 
 namespace RhSolutions.AddIn
 {
-    public class RhSolutionsAddIn : IExcelAddIn
+    public sealed class RhSolutionsAddIn : IExcelAddIn
     {
         public static Application Excel { get; private set; }
         public static ServiceProvider ServiceProvider { get; set; }
@@ -17,15 +17,16 @@ namespace RhSolutions.AddIn
         public void AutoOpen()
         {
             IServiceCollection Services = new ServiceCollection();
-            Excel = (Application)ExcelDnaUtil.Application;
 
             Services.AddHttpClient()
                 .AddSingleton<IDatabaseClient, RhDatabaseClient>()
-                .AddSingleton<IAddInConfiguration, AddInConfiguration>();
+                .AddSingleton<IAddInConfiguration, AddInConfiguration>()
+                .AddSingleton(ExcelDnaUtil.Application);
 
             ServiceProvider = Services.BuildServiceProvider();
             Configuration = ServiceProvider.GetService<IAddInConfiguration>();
-                        
+            Excel = ServiceProvider.GetService<Application>();
+
             IntelliSenseServer.Install();
             EventsUtil.Initialize();