diff --git a/Toolkit.Foundation/ObservableCollection.cs b/Toolkit.Foundation/ObservableCollection.cs
index a86a127..1682f1d 100644
--- a/Toolkit.Foundation/ObservableCollection.cs
+++ b/Toolkit.Foundation/ObservableCollection.cs
@@ -81,7 +81,7 @@ public partial class ObservableCollection<TItem> :
     [ObservableProperty]
     private int count;
 
-    private IDispatcher dispatcher;
+    private readonly IDispatcher dispatcher;
 
     [ObservableProperty]
     private bool initialized;