diff --git a/inc/caldav-REPORT-sync-collection.php b/inc/caldav-REPORT-sync-collection.php
index 2e641867..d32126fa 100644
--- a/inc/caldav-REPORT-sync-collection.php
+++ b/inc/caldav-REPORT-sync-collection.php
@@ -1,4 +1,14 @@
 <?php
+/**
+* CalDAV Server - handle sync-collection report (draft-daboo-webdav-sync-01)
+*
+* @package   davical
+* @subpackage   caldav
+* @author    Andrew McMillan <andrew@mcmillan.net.nz>
+* @copyright Morphoss Ltd - http://www.morphoss.com/
+* @license   http://gnu.org/copyleft/gpl.html GNU GPL v2 or later
+*/
+
 require("DAVResource.php");
 $responses = array();
 
@@ -23,7 +33,7 @@ foreach( $props AS $k => $v ) {
 function display_status( $status_code ) {
   return sprintf( 'HTTP/1.1 %03d %s', intval($status_code), getStatusMessage($status_code) );
 }
-  
+
 $sql = "SELECT new_sync_token(?,?)";
 $qry = new PgQuery($sql, $sync_token, $request->CollectionId());
 if ( !$qry->Exec("REPORT",__LINE__,__FILE__) || $qry->rows <= 0 ) {
@@ -38,31 +48,67 @@ SELECT *, 201 AS sync_status FROM collection
             LEFT JOIN caldav_data USING (collection_id)
             LEFT JOIN calendar_item USING (dav_id)
      WHERE collection.collection_id = ?
+   ORDER BY collection.collection_id, caldav_data.dav_id
 EOSQL;
   $qry = new PgQuery($sql, $request->CollectionId());
 }
 else {
   $sql = <<<EOSQL
 SELECT * FROM collection LEFT JOIN sync_changes USING(collection_id)
-                         LEFT JOIN calendar_item USING (dav_id)
-                         LEFT JOIN caldav_data USING (dav_id)
+                         LEFT JOIN calendar_item USING (collection_id,dav_id)
+                         LEFT JOIN caldav_data USING (collection_id,dav_id)
      WHERE collection.collection_id = ?
-      AND sync_time > (SELECT modification_time FROM sync_tokens WHERE sync_token = ?)
+       AND sync_time > (SELECT modification_time FROM sync_tokens WHERE sync_token = ?)
+   ORDER BY collection.collection_id, sync_changes.dav_id, sync_changes.sync_time
 EOSQL;
   $qry = new PgQuery($sql, $request->CollectionId(), $sync_token);
 }
 
+$last_dav_id = -1;
+$first_status = 0;
+
 if ( $qry->Exec("REPORT",__LINE__,__FILE__) ) {
   while( $object = $qry->Fetch() ) {
-    $resultset = array(
-      new XMLElement( 'href', ConstructURL($object->dav_name) ), 
-      new XMLElement( 'status', display_status($object->sync_status) )
-    );
-    if ( $status != 404 ) {
-      $dav_resource = new DAVResource($object);
-      $resultset = array_merge( $resultset, $dav_resource->GetPropStat($proplist) );
-    } 
-    $responses[] = new XMLElement( 'sync-response', $resultset );
+    if ( $object->dav_id == $last_dav_id ) {
+      /** The complex case: this is the second or subsequent for this dav_id */
+      if ( $object->sync_status == 404 ) {
+        if ( $first_action == 201 ) {
+          array_pop($responses);
+          $last_dav_id = -1;
+          $first_status = 0;
+        }
+        else {
+          array_pop($responses);
+          $resultset = array(
+            new XMLElement( 'href', ConstructURL($object->dav_name) ),
+            new XMLElement( 'status', display_status($object->sync_status) )
+          );
+          $responses[] = new XMLElement( 'sync-response', $resultset );
+          $first_status = 404;
+        }
+      }
+      /** Else:
+       *    the object existed at start and we have multiple modifications,
+       *  or,
+       *    the object didn't exist at start and we have subsequent modifications,
+       *  but:
+       *    in either case we simply stick with our first report.
+       */
+    }
+    else {
+      /** The simple case: this is the first one for this dav_id */
+      $resultset = array(
+        new XMLElement( 'href', ConstructURL($object->dav_name) ),
+        new XMLElement( 'status', display_status($object->sync_status) )
+      );
+      if ( $object->sync_status != 404 ) {
+        $dav_resource = new DAVResource($object);
+        $resultset = array_merge( $resultset, $dav_resource->GetPropStat($proplist) );
+      }
+      $responses[] = new XMLElement( 'sync-response', $resultset );
+      $first_status = $object->sync_status;
+      $last_dav_id  = $object->dav_id;
+    }
   }
   $responses[] = new XMLElement( 'sync-token', $new_token );
 }