--- a/suite/mailnews/addrbook/abTrees.js
+++ b/suite/mailnews/addrbook/abTrees.js
@@ -158,21 +158,21 @@ directoryTreeView.prototype =
     if (aJSONFile)
     {
       // Write out our json file...
       let data = JSON.stringify(this._persistOpenMap);
       let file = Components.classes["@mozilla.org/file/directory_service;1"]
                            .getService(Components.interfaces.nsIProperties)
                            .get("ProfD", Components.interfaces.nsIFile);
       file.append(aJSONFile);
-      let foStream = Components.classes["@mozilla.org/network/file-output-stream;1"]
+      let foStream = Components.classes["@mozilla.org/network/safe-file-output-stream;1"]
                                .createInstance(Components.interfaces.nsIFileOutputStream);
-
       foStream.init(file, 0x02 | 0x08 | 0x20, 0666, 0);
       foStream.write(data, data.length);
+      foStream.QueryInterface(Components.interfaces.nsISafeOutputStream).finish();
       foStream.close();
     }
   },
 
   // Override the dnd methods for those functions in abDragDrop.js
   canDrop: function dtv_canDrop(aIndex, aOrientation)
   {
     return abDirTreeObserver.canDrop(aIndex, aOrientation);