diff --git a/src/Avalonia.X11/X11PlatformLifetimeEvents.cs b/src/Avalonia.X11/X11PlatformLifetimeEvents.cs
index 4e20f68451..a8beb8bbd6 100644
--- a/src/Avalonia.X11/X11PlatformLifetimeEvents.cs
+++ b/src/Avalonia.X11/X11PlatformLifetimeEvents.cs
@@ -241,6 +241,6 @@ namespace Avalonia.X11
                 IntPtr.Zero);
         }
 
-        public event EventHandler<ShutdownRequestedEventArgs> ShutdownRequested = null!;
+        public event EventHandler<ShutdownRequestedEventArgs>? ShutdownRequested;
     }
 }