diff --git a/mozilla/calendar/base/src/calItemBase.js b/mozilla/calendar/base/src/calItemBase.js
index 25a4b81ddf4..f1d4e4314b1 100644
--- a/mozilla/calendar/base/src/calItemBase.js
+++ b/mozilla/calendar/base/src/calItemBase.js
@@ -280,6 +280,10 @@ calItemBase.prototype = {
         "DTALARM": true,
         "DTSTAMP": true,
         "X-MOZILLA-GENERATION": true,
+        "RRULE": true,
+        "EXDATE": true,
+        "RDATE": true,
+        "ATTENDEE": true,
     },
 
     mapPropsFromICS: function(icalcomp, propmap) {
diff --git a/mozilla/calendar/test/homegrown/ics2ics.js b/mozilla/calendar/test/homegrown/ics2ics.js
new file mode 100644
index 00000000000..964d3d223c3
--- /dev/null
+++ b/mozilla/calendar/test/homegrown/ics2ics.js
@@ -0,0 +1,26 @@
+var str = "BEGIN:VCALENDAR\n";
+   str += "BEGIN:VEVENT\n";
+   str += "CREATED:20050104T211235\n";
+   str += "LAST-MODIFIED:20050108T182742\n";
+   str += "DTSTAMP:20050104T211235\n";
+   str += "UID:uuid:1104873174977\n";
+   str += "SUMMARY:teste\n";
+   str += "DTSTART:20050107T094500\n";
+   str += "DTEND:20050107T104500\n";
+   str += "RRULE:FREQ=DAILY;COUNT=43;INTERVAL=5\n";
+   str += "ATTENDEE:MAILTO:test@example.com\n";
+   str += "END:VEVENT\n";
+   str += "END:VCALENDAR\n";
+
+var icsServ = Components.classes["@mozilla.org/calendar/ics-service;1"]
+                        .getService(Components.interfaces.calIICSService);
+
+var calComp = icsServ.parseICS(str);
+var subComp = calComp.getFirstSubcomponent("VEVENT");
+var event = Components.classes["@mozilla.org/calendar/event;1"]
+                      .createInstance(Components.interfaces.calIEvent);
+event.icalComponent = subComp;
+
+var newCalComp = event.icalComponent;
+dump(newCalComp.serializeToICS());
+