diff --git a/ProjectAirplaneWithRadar/ProjectAirplaneWithRadar/FormAirplaneWithRadar.cs b/ProjectAirplaneWithRadar/ProjectAirplaneWithRadar/FormAirplaneWithRadar.cs
index 0e1a4bd..b4d5bcf 100644
--- a/ProjectAirplaneWithRadar/ProjectAirplaneWithRadar/FormAirplaneWithRadar.cs
+++ b/ProjectAirplaneWithRadar/ProjectAirplaneWithRadar/FormAirplaneWithRadar.cs
@@ -2,7 +2,7 @@ namespace ProjectAirplaneWithRadar
 {
     public partial class FormAirplaneWithRadar : Form
     {
-        private DrawningAirplaneWithRadar _drawningAirplaneWithRadar;
+        private DrawningAirplaneWithRadar? _drawningAirplaneWithRadar;
         private void Draw()
         {
             if (_drawningAirplaneWithRadar == null)