diff --git a/ChatController/ChatMainControl.xaml.cs b/ChatController/ChatMainControl.xaml.cs
index 6be474c..6aec4da 100644
--- a/ChatController/ChatMainControl.xaml.cs
+++ b/ChatController/ChatMainControl.xaml.cs
@@ -411,7 +411,7 @@ namespace ChatController
 
                 contact.IsNewMessage = false;
 
-                var shouldChangeIcon = _ContactList.Any(contactDependencyObject => contactDependencyObject.Contact.IsNewMessage);
+                var shouldChangeIcon = _ContactList.Any(contactDependencyObject => contactDependencyObject.Contact?.IsNewMessage ?? false);
                 if(shouldChangeIcon)
                 {
                     ContainingWindow.Icon = Utils.ConvertIconToImageSource(Resource.ownchat_favicon);
@@ -421,11 +421,14 @@ namespace ChatController
 
                 OnPropertyChanged(nameof(IsSendButtonEnabled));
 
-                foreach(ContactDependencyObject item in Clientlist.Items)
+                if(!(Clientlist is null))
                 {
-                    if(item.Contact.Equals(contact))
+                    foreach(var obj in Clientlist.Items)
                     {
-                        Clientlist.SelectedItem = item;
+                        if(obj is ContactDependencyObject contactDependencyObject && Equals(contactDependencyObject.Contact, contact))
+                        {
+                            Clientlist.SelectedItem = obj;
+                        }
                     }
                 }