diff --git a/clutter/clutter-types.h b/clutter/clutter-types.h
index e7ede1452..30205686c 100644
--- a/clutter/clutter-types.h
+++ b/clutter/clutter-types.h
@@ -536,6 +536,10 @@ void             clutter_actor_box_set_size       (ClutterActorBox       *box,
  * @height: height of an actor
  *
  * The rectangle containing an actor's bounding box, measured in pixels.
+ *
+ * <warning>You should not use #ClutterGeometry, or operate on its fields
+ * directly; you should use #cairo_rectangle_int_t or #ClutterRect if you
+ * need a rectangle type, depending on the precision required.</warning>
  */
 struct _ClutterGeometry
 {