diff --git a/mozilla/calendar/prototypes/wcap/sun-calendar-event-dialog.css b/mozilla/calendar/prototypes/wcap/sun-calendar-event-dialog.css
index f4fbc146c34..38505913813 100644
--- a/mozilla/calendar/prototypes/wcap/sun-calendar-event-dialog.css
+++ b/mozilla/calendar/prototypes/wcap/sun-calendar-event-dialog.css
@@ -186,6 +186,7 @@ timezone-page {
     -moz-user-focus: none;
 }
 
+/* This definition is only required for MOZILLA_1_8_BRANCH */
 .textbox-addressingWidget[noMatchesFound="true"] {
     color: red;
 }