diff --git a/gtk/gtkgesture.c b/gtk/gtkgesture.c
index e1f03d8dd9..30d944a76c 100644
--- a/gtk/gtkgesture.c
+++ b/gtk/gtkgesture.c
@@ -318,7 +318,7 @@ _update_widget_coordinates (GtkGesture *gesture,
   gdk_event_get_coords (data->event, &event_x, &event_y);
   window = data->event->any.window;
 
-  while (window != event_widget_window)
+  while (window && window != event_widget_window)
     {
       gdk_window_get_position (window, &wx, &wy);
       event_x += wx;
@@ -326,6 +326,9 @@ _update_widget_coordinates (GtkGesture *gesture,
       window = gdk_window_get_effective_parent (window);
     }
 
+  if (!window)
+    return;
+
   if (!gtk_widget_get_has_window (event_widget))
     {
       gtk_widget_get_allocation (event_widget, &allocation);