diff --git a/calendar/base/public/calIDuration.idl b/calendar/base/public/calIDuration.idl
index 7e11da0bee36..b47be1cc9421 100644
--- a/calendar/base/public/calIDuration.idl
+++ b/calendar/base/public/calIDuration.idl
@@ -124,5 +124,5 @@ interface calIDuration : nsISupports
   /**
    * This object as an iCalendar DURATION string
    */
-  readonly attribute ACString icalString;
+  attribute ACString icalString;
 };
diff --git a/calendar/base/src/calDuration.cpp b/calendar/base/src/calDuration.cpp
index 5c709ec85690..592e36465777 100644
--- a/calendar/base/src/calDuration.cpp
+++ b/calendar/base/src/calDuration.cpp
@@ -294,3 +294,10 @@ calDuration::GetIcalString(nsACString& aResult)
 
     return NS_ERROR_OUT_OF_MEMORY;
 }
+
+NS_IMETHODIMP
+calDuration::SetIcalString(const nsACString& aIcalString)
+{
+    mDuration = icaldurationtype_from_string(nsPromiseFlatCString(aIcalString).get());
+    return NS_OK;
+}
diff --git a/calendar/base/src/calItemBase.js b/calendar/base/src/calItemBase.js
index a26a4bfa36a7..0832c5fb687b 100644
--- a/calendar/base/src/calItemBase.js
+++ b/calendar/base/src/calItemBase.js
@@ -516,6 +516,34 @@ calItemBase.prototype = {
         }
         this.mRecurrenceInfo = rec;
 
+        var alarmComp = icalcomp.getFirstSubcomponent("VALARM");
+        if (alarmComp) {
+            var triggerProp = alarmComp.getFirstProperty("TRIGGER");
+            var duration = Components.classes["@mozilla.org/calendar/duration;1"]
+                                     .createInstance(Components.interfaces.calIDuration);
+            duration.icalString = triggerProp.stringValue;
+
+            if (duration.minutes) {
+                this.setProperty("alarmLength", duration.minutes);
+                this.setProperty("alarmUnits", "minutes");
+            } else if (duration.hours) {
+                this.setProperty("alarmLength", duration.hours);
+                this.setProperty("alarmUnits", "hours");
+            } else if (duration.days) {
+                this.setProperty("alarmLength", duration.days);
+                this.setProperty("alarmUnits", "days");
+            }
+
+            var related = triggerProp.getParameter("RELATED");
+            if (related && related == "END")
+                this.setProperty("alarmRelated", "END");
+            else
+                this.setProperty("alarmRelated", "START");
+
+            var email = alarmComp.getFirstProperty("X-EMAILADDRESS");
+            if (email)
+                this.setProperty("alarmEmailAddress", email);
+        }
     },
 
     importUnpromotedProperties: function (icalcomp, promoted) {
@@ -561,7 +589,33 @@ calItemBase.prototype = {
                 icalcomp.addProperty(ritems[i].icalProperty);
             }
         }
+        
+        if (this.alarmTime) {
+            const icssvc = Components.classes["@mozilla.org/calendar/ics-service;1"]
+                                     .getService(Components.interfaces.calIICSService);
+            var alarmComp = icssvc.createIcalComponent("VALARM");
 
+            var duration = Components.classes["@mozilla.org/calendar/duration;1"]
+                                     .createInstance(Components.interfaces.calIDuration);
+            duration.isNegative = true;
+            duration[this.getProperty("alarmUnits")] = this.getProperty("alarmLength");
+
+            var triggerProp = icssvc.createIcalProperty("TRIGGER");
+            triggerProp.stringValue = duration.icalString;
+
+            if (this.getProperty("alarmRelated") == "END") 
+                triggerProp.setParameter("RELATED", "END");
+
+            alarmComp.addProperty(triggerProp);
+
+            if (this.getProperty("alarmEmailAddress")) {
+                var emailProp = icssvc.createIcalProperty("X-EMAILADDRESS");
+                emailProp.stringValue = this.getProperty("alarmEmailAddress");
+                alarmComp.addProperty(emailProp);
+            }
+
+            icalcomp.addSubcomponent(alarmComp);
+        }
     },
     
     getOccurrencesBetween: function(aStartDate, aEndDate, aCount) {