diff --git a/src/ElectronNET.API/Converter/TitleBarOverlayConverter.cs b/src/ElectronNET.API/Converter/TitleBarOverlayConverter.cs
index 42d6ddb..58bf53d 100644
--- a/src/ElectronNET.API/Converter/TitleBarOverlayConverter.cs
+++ b/src/ElectronNET.API/Converter/TitleBarOverlayConverter.cs
@@ -26,6 +26,7 @@ public class TitleBarOverlayConverter : JsonConverter<TitleBarOverlay>
     {
         if (value is null)
         {
+            writer.WriteUndefined();
             return;
         }