Couldn't load plugin sextante due an error when calling its classFactory() method

Traceback (most recent call last):
  File "C:/OSGeo4W/apps/qgis-dev/./python\qgis\utils.py", line 204, in startPlugin
    plugins[packageName] = package.classFactory(iface)
  File "C:/OSGeo4W/apps/qgis-dev/./python/plugins\sextante\__init__.py", line 50, in classFactory
    from sextante.SextantePlugin import SextantePlugin
  File "C:/OSGeo4W/apps/qgis-dev/./python\qgis\utils.py", line 453, in _import
    mod = _builtin_import(name, globals, locals, fromlist, level)
  File "C:/OSGeo4W/apps/qgis-dev/./python/plugins\sextante\SextantePlugin.py", line 37, in 
    from sextante.gui.SextanteToolbox import SextanteToolbox
  File "C:/OSGeo4W/apps/qgis-dev/./python\qgis\utils.py", line 453, in _import
    mod = _builtin_import(name, globals, locals, fromlist, level)
  File "C:/OSGeo4W/apps/qgis-dev/./python/plugins\sextante\gui\SextanteToolbox.py", line 44, in 
    _fromUtf8 = QString.fromUtf8
NameError: name 'QString' is not defined

Python version:
2.7.4 (default, Apr  6 2013, 19:54:46) [MSC v.1500 32 bit (Intel)]


QGIS version:
1.9.0-Master Master, 95dcd96

Python path: ['C:/OSGeo4W/apps/qgis-dev/./python', 'C:\\Users\\Aren Cambre/.qgis2/python', 'C:\\Users\\Aren Cambre/.qgis2/python/plugins', 'C:/OSGeo4W/apps/qgis-dev/./python/plugins', 'C:\\OSGeo4W\\bin\\python27.zip', 'C:\\OSGeo4W\\apps\\Python27\\DLLs', 'C:\\OSGeo4W\\apps\\Python27\\lib', 'C:\\OSGeo4W\\apps\\Python27\\lib\\plat-win', 'C:\\OSGeo4W\\apps\\Python27\\lib\\lib-tk', 'C:\\OSGeo4W\\bin', 'C:\\OSGeo4W\\apps\\Python27', 'C:\\OSGeo4W\\apps\\Python27\\lib\\site-packages', 'C:\\OSGeo4W\\apps\\Python27\\lib\\site-packages\\PIL', 'C:\\OSGeo4W\\apps\\Python27\\lib\\site-packages\\win32', 'C:\\OSGeo4W\\apps\\Python27\\lib\\site-packages\\win32\\lib', 'C:\\OSGeo4W\\apps\\Python27\\lib\\site-packages\\Pythonwin', 'C:\\OSGeo4W\\apps\\Python27\\lib\\site-packages\\wx-2.8-msw-unicode', 'C:\\OSGeo4W\\apps\\qgis-dev\\python\\plugins\\fTools\\tools']