diff --git a/Flow.Launcher/ViewModel/ResultsViewModel.cs b/Flow.Launcher/ViewModel/ResultsViewModel.cs
index 55dea7440..2a0818b7d 100644
--- a/Flow.Launcher/ViewModel/ResultsViewModel.cs
+++ b/Flow.Launcher/ViewModel/ResultsViewModel.cs
@@ -249,7 +249,7 @@ namespace Flow.Launcher.ViewModel
 
             protected void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
             {
-                CollectionChanged(this, e);
+                CollectionChanged?.Invoke(this, e);
             }
 
             public void BulkAddAll(List<ResultViewModel> resultViews)