diff --git a/Source/Editor/CustomEditors/Editors/ModelInstanceEntryEditor.cs b/Source/Editor/CustomEditors/Editors/ModelInstanceEntryEditor.cs
index 568a57794..f9ccf548a 100644
--- a/Source/Editor/CustomEditors/Editors/ModelInstanceEntryEditor.cs
+++ b/Source/Editor/CustomEditors/Editors/ModelInstanceEntryEditor.cs
@@ -76,7 +76,7 @@ namespace FlaxEditor.CustomEditors.Editors
 
         private void OnSelectedMaterialChanged()
         {
-            if (_isRefreshing)
+            if (_isRefreshing || _modelInstance == null)
                 return;
             _isRefreshing = true;
             var slots = _modelInstance.MaterialSlots;
diff --git a/Source/Editor/GUI/AssetPicker.cs b/Source/Editor/GUI/AssetPicker.cs
index 84f58daf1..9e8e0485e 100644
--- a/Source/Editor/GUI/AssetPicker.cs
+++ b/Source/Editor/GUI/AssetPicker.cs
@@ -75,6 +75,9 @@ namespace FlaxEditor.GUI
         /// </summary>
         protected virtual void OnSelectedItemChanged()
         {
+            if (IsDisposing)
+                return;
+
             // Update tooltip
             string tooltip;
             if (Validator.SelectedItem is AssetItem assetItem)