diff --git a/src/Avalonia.X11/X11Window.cs b/src/Avalonia.X11/X11Window.cs
index 7cf4d3e2bb..9751c9b19c 100644
--- a/src/Avalonia.X11/X11Window.cs
+++ b/src/Avalonia.X11/X11Window.cs
@@ -1250,10 +1250,10 @@ namespace Avalonia.X11
                     ptr1 = l0,
                     ptr2 = l1 ?? IntPtr.Zero,
                     ptr3 = l2 ?? IntPtr.Zero,
-                    ptr4 = l3 ?? IntPtr.Zero
+                    ptr4 = l3 ?? IntPtr.Zero,
+                    ptr5 = l4 ?? IntPtr.Zero
                 }
             };
-            xev.ClientMessageEvent.ptr4 = l4 ?? IntPtr.Zero;
             XSendEvent(_x11.Display, _x11.RootWindow, false,
                 new IntPtr((int)(EventMask.SubstructureRedirectMask | EventMask.SubstructureNotifyMask)), ref xev);