diff --git a/doc/cookbook/events.xml b/doc/cookbook/events.xml
index 5b6683b39..802885fab 100644
--- a/doc/cookbook/events.xml
+++ b/doc/cookbook/events.xml
@@ -609,6 +609,7 @@ _scroll_event_cb (ClutterActor *viewport,
              viewport_height - scrollable_height,
              0.0);
 
+  /* animate the change to the scrollable's y coordinate */
   clutter_actor_animate (scrollable,
                          CLUTTER_EASE_OUT_CUBIC,
                          300,
diff --git a/doc/cookbook/examples/events-mouse-scroll.c b/doc/cookbook/examples/events-mouse-scroll.c
index d8d6163f6..bce9c40b4 100644
--- a/doc/cookbook/examples/events-mouse-scroll.c
+++ b/doc/cookbook/examples/events-mouse-scroll.c
@@ -50,6 +50,7 @@ _scroll_event_cb (ClutterActor *viewport,
              viewport_height - scrollable_height,
              0.0);
 
+  /* animate the change to the scrollable's y coordinate */
   clutter_actor_animate (scrollable,
                          CLUTTER_EASE_OUT_CUBIC,
                          300,