--- a/uriloader/exthandler/nsHandlerService.js
+++ b/uriloader/exthandler/nsHandlerService.js
@@ -15,16 +15,17 @@
  *
  * The Initial Developer of the Original Code is Mozilla.
  * Portions created by the Initial Developer are Copyright (C) 2007
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
  *   Myk Melez <myk@mozilla.org>
  *   Dan Mosedale <dmose@mozilla.org>
+ *   Florian Queze <florian@queze.net>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  * in which case the provisions of the GPL or the LGPL are applicable instead
  * of those above. If you wish to allow use of your version of this file only
  * under the terms of either the GPL or the LGPL, and not to allow others to
  * use your version of this file under the terms of the MPL, indicate your
@@ -669,28 +670,28 @@ HandlerService.prototype = {
     var newHandlerApps =
       aHandlerInfo.possibleApplicationHandlers.enumerate();
     while (newHandlerApps.hasMoreElements()) {
       let handlerApp =
         newHandlerApps.getNext().QueryInterface(Ci.nsIHandlerApp);
       let handlerAppID = this._getPossibleHandlerAppID(handlerApp);
       if (!this._hasResourceAssertion(infoID, NC_POSSIBLE_APP, handlerAppID)) {
         this._storeHandlerApp(handlerAppID, handlerApp);
-        this._addResourceTarget(infoID, NC_POSSIBLE_APP, handlerAppID);
+        this._addResourceAssertion(infoID, NC_POSSIBLE_APP, handlerAppID);
       }
       delete currentHandlerApps[handlerAppID];
     }
 
     // Finally, remove any old handler apps that aren't being used anymore,
     // and if those handler apps aren't being used by any other type either,
     // then completely remove their record from the datastore so we don't
     // leave it clogged up with information about handler apps we don't care
     // about anymore.
     for (let handlerAppID in currentHandlerApps) {
-      this._removeTarget(infoID, NC_POSSIBLE_APP, handlerAppID);
+      this._removeResourceAssertion(infoID, NC_POSSIBLE_APP, handlerAppID);
       if (!this._existsResourceTarget(NC_POSSIBLE_APP, handlerAppID))
         this._removeAssertions(handlerAppID);
     }
   },
 
   /**
    * Store the given handler app.
    *
@@ -1143,26 +1144,44 @@ HandlerService.prototype = {
    * The difference between this method and _setResource is that this one adds
    * an assertion even if one already exists, which allows its callers to make
    * sets of assertions (i.e. to set a property to multiple targets).
    *
    * @param sourceURI   {string} the URI of the source
    * @param propertyURI {string} the URI of the property
    * @param targetURI   {string} the URI of the target
    */
-  _addResourceTarget: function HS__addResourceTarget(sourceURI, propertyURI,
-                                                     targetURI) {
+  _addResourceAssertion: function HS__addResourceAssertion(sourceURI,
+                                                           propertyURI,
+                                                           targetURI) {
     var source = this._rdf.GetResource(sourceURI);
     var property = this._rdf.GetResource(propertyURI);
     var target = this._rdf.GetResource(targetURI);
     
     this._ds.Assert(source, property, target, true);
   },
 
   /**
+   * Remove an assertion with a resource target.
+   *
+   * @param sourceURI   {string} the URI of the source
+   * @param propertyURI {string} the URI of the property
+   * @param targetURI   {string} the URI of the target
+   */
+  _removeResourceAssertion: function HS__removeResourceAssertion(sourceURI,
+                                                                 propertyURI,
+                                                                 targetURI) {
+    var source = this._rdf.GetResource(sourceURI);
+    var property = this._rdf.GetResource(propertyURI);
+    var target = this._rdf.GetResource(targetURI);
+
+    this._ds.Unassert(source, property, target);
+  },
+
+  /**
    * Whether or not a property of an RDF source has a given resource target.
    * 
    * @param sourceURI   {string} the URI of the source
    * @param propertyURI {string} the URI of the property
    * @param targetURI   {string} the URI of the target
    *
    * @returns {boolean} whether or not there is such an assertion
    */