diff --git a/inc/caldav-PROPFIND.php b/inc/caldav-PROPFIND.php
index 72e4b808..50aac4f4 100644
--- a/inc/caldav-PROPFIND.php
+++ b/inc/caldav-PROPFIND.php
@@ -117,6 +117,12 @@ function namespace_array() {
 }
 
 
+function calendar_server_tag( $tag ) {
+  add_namespace("A", "http://calendarserver.org/ns/");
+  return ns_tag( $tag, 'http://calendarserver.org/ns/' );
+}
+
+
 function caldav_tag( $tag ) {
   return ns_tag( $tag, 'urn:ietf:params:xml:ns:caldav' );
 }
@@ -158,6 +164,7 @@ foreach( $request->xml_tags AS $k => $v ) {
     case 'GETCONTENTLENGTH':               /** getcontentlength- should work fine */
     case 'GETCONTENTTYPE':                 /** getcontenttype  - should work fine */
     case 'GETETAG':                        /** getetag         - should work fine */
+    case 'GETCTAG':                        /** Calendar Server extension like etag - should work fine (we just return etag) */
     case 'SUPPORTEDLOCK':                  /** supportedlock   - should work fine */
     case 'PRINCIPAL-URL':                  /** principal-url   - should work fine */
     case 'RESOURCETYPE':                   /** resourcetype    - should work fine */
@@ -291,12 +298,10 @@ function add_principal_properties( &$prop, &$not_found, &$denied ) {
   }
 
   if ( isset($attribute_list['DROPBOX-HOME-URL'] ) ) {
-    add_namespace("A", "http://calendarserver.org/ns/");
-    $prop->NewElement("A:dropbox-home-url", new XMLElement('href', $request->principal->dropbox_url) );
+    $prop->NewElement(calendar_server_tag("dropbox-home-url"), new XMLElement('href', $request->principal->dropbox_url) );
   }
   if ( isset($attribute_list['NOTIFICATIONS-URL'] ) ) {
-    add_namespace("A", "http://calendarserver.org/ns/");
-    $prop->NewElement("A:notifications-url", new XMLElement('href', $request->principal->notifications_url) );
+    $prop->NewElement(calendar_server_tag("notifications-url"), new XMLElement('href', $request->principal->notifications_url) );
   }
 
   if ( isset($attribute_list['CALENDAR-USER-ADDRESS-SET'] ) ) {
@@ -379,6 +384,10 @@ function collection_to_xml( $collection ) {
   if ( isset($attribute_list['ALLPROP']) || isset($attribute_list['GETETAG']) ) {
     $prop->NewElement("getetag", '"'.$collection->dav_etag.'"' );
   }
+  if ( isset($attribute_list['GETCTAG']) ) {
+    // Calendar Server extension which only applies to collections.  We return the etag, which does the needful.
+    $prop->NewElement(calendar_server_tag('getctag'),$collection->dav_etag );
+  }
   if ( isset($attribute_list['ALLPROP']) || isset($attribute_list['CURRENT-USER-PRIVILEGE-SET']) ) {
     $prop->NewElement("current-user-privilege-set", privileges($request->permissions) );
   }
diff --git a/testing/tests/regression-suite/503-iCal-PROPFIND.result b/testing/tests/regression-suite/503-iCal-PROPFIND.result
index 3cc4b197..f07aa16f 100644
--- a/testing/tests/regression-suite/503-iCal-PROPFIND.result
+++ b/testing/tests/regression-suite/503-iCal-PROPFIND.result
@@ -1,12 +1,12 @@
 HTTP/1.1 207 Multi-Status
 Date: Dow, 01 Jan 2000 00:00:00 GMT
 DAV: 1, 2, access-control, calendar-access
-ETag: "45e62f9b3b6b55ac40673d4ef35948b9"
-Content-Length: 623
+ETag: "f5bcdac4101184e674bfb4112dfe4b0c"
+Content-Length: 666
 Content-Type: text/xml; charset="utf-8"
 
 <?xml version="1.0" encoding="utf-8" ?>
-<multistatus xmlns="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav" xmlns:C1="http://calendarserver.org/ns/" xmlns:A="http://apple.com/ns/ical/">
+<multistatus xmlns="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav" xmlns:A="http://calendarserver.org/ns/" xmlns:A1="http://apple.com/ns/ical/">
  <response>
   <href>/caldav.php/user1/home/</href>
   <propstat>
@@ -16,13 +16,13 @@ Content-Type: text/xml; charset="utf-8"
      <C:calendar/>
     </resourcetype>
     <displayname>home</displayname>
+    <A:getctag>faf25336de0e470a54075c14cbcf5272</A:getctag>
    </prop>
    <status>HTTP/1.1 200 OK</status>
   </propstat>
   <propstat>
    <prop>
-    <C1:getctag/>
-    <A:calendar-color/>
+    <A1:calendar-color/>
     <C:calendar-description/>
    </prop>
    <status>HTTP/1.1 404 Not Found</status>