diff --git a/src/Cody.VisualStudio/Services/DocumentsSyncService.cs b/src/Cody.VisualStudio/Services/DocumentsSyncService.cs
index bea346c..9bc5d12 100644
--- a/src/Cody.VisualStudio/Services/DocumentsSyncService.cs
+++ b/src/Cody.VisualStudio/Services/DocumentsSyncService.cs
@@ -10,6 +10,7 @@
 using Microsoft.VisualStudio.TextManager.Interop;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 
@@ -52,6 +53,7 @@ public void Initialize()
                 try
                 {
                     uint activeCookie = 0;
+                    AssertThatNoOpenedDocuments();
                     foreach (var frame in GetOpenDocuments())
                     {
                         if (frame.GetProperty((int)__VSFPROPID.VSFPROPID_DocCookie, out object cookie) != VSConstants.S_OK) continue;
@@ -83,6 +85,12 @@ public void Initialize()
             });
         }
 
+        private void AssertThatNoOpenedDocuments()
+        {
+            Debug.Assert(openNotificationSend.Count == 0, $"{nameof(openNotificationSend)} is {openNotificationSend}, but it should be ZERO!");
+            Debug.Assert(isSubscribed.Count == 0, $"{nameof(isSubscribed)} is {isSubscribed}, but it should be ZERO!");
+        }
+
         private IVsTextView GetVsTextView(IVsWindowFrame windowFrame)
         {
             windowFrame.GetProperty((int)__VSFPROPID.VSFPROPID_DocView, out var pvar);