diff --git a/panel/panel-window.c b/panel/panel-window.c
index 58208cbcb6ffbb3d15b7e427357d98620f1f8bc4..803092c1470f5d47dc2a5c6eeebf394dfe8ac9dc 100644
--- a/panel/panel-window.c
+++ b/panel/panel-window.c
@@ -3444,7 +3444,8 @@ panel_window_active_window_monitors_idle (gpointer data)
 {
   PanelWindow *window = data;
 
-  panel_window_active_window_monitors (window->xfw_active_window, NULL, window);
+  if (window->xfw_active_window != NULL)
+    panel_window_active_window_monitors (window->xfw_active_window, NULL, window);
 
   return FALSE;
 }