diff --git a/mozilla/calendar/base/content/calendar-recurrence-dialog.js b/mozilla/calendar/base/content/calendar-recurrence-dialog.js
index 4adf196dea6..261685da3ed 100644
--- a/mozilla/calendar/base/content/calendar-recurrence-dialog.js
+++ b/mozilla/calendar/base/content/calendar-recurrence-dialog.js
@@ -48,6 +48,8 @@ function onLoad()
 
     updateDeck();
 
+    updateDuration();
+
     opener.setCursor("auto");
 
     self.focus();
@@ -203,3 +205,23 @@ function updateDeck()
     document.getElementById("period-deck").selectedIndex = Number(getElementValue("period-list"));
 }
 
+function updateDuration()
+{
+    var durationSelection = document.getElementById("recurrence-duration").selectedItem.value;
+    if (durationSelection == "forever") {
+    }
+
+    if (durationSelection == "ntimes") {
+        setElementValue("repeat-ntimes-count", false, "disabled");
+        setElementValue("repeat-ntimes-units", false, "disabled");
+    } else {
+        setElementValue("repeat-ntimes-count", "true", "disabled");
+        setElementValue("repeat-ntimes-units", "true", "disabled");
+    }
+
+    if (durationSelection == "until") {
+        setElementValue("repeat-until-date", false, "disabled");
+    } else {
+        setElementValue("repeat-until-date", "true", "disabled");
+    }
+}
diff --git a/mozilla/calendar/base/content/calendar-recurrence-dialog.xul b/mozilla/calendar/base/content/calendar-recurrence-dialog.xul
index 4bd2725a87c..d85f2b0621e 100644
--- a/mozilla/calendar/base/content/calendar-recurrence-dialog.xul
+++ b/mozilla/calendar/base/content/calendar-recurrence-dialog.xul
@@ -135,7 +135,7 @@
   <spacer flex="1"/>
 
   <vbox>
-    <radiogroup id="recurrence-duration">
+    <radiogroup id="recurrence-duration" oncommand="updateDuration()">
       <grid flex="1">
         <columns>
           <column/>
@@ -152,7 +152,7 @@
             <hbox>
               <textbox id="repeat-ntimes-count" size="3"/>
               <spacer flex="0.5"/>
-              <menulist>
+              <menulist id="repeat-ntimes-units">
                 <menupopup>
                   <menuitem label="day(s)"/>
                   <menuitem label="week(s)"/>