--- a/web/formwidgets.py	Tue Mar 12 19:24:43 2013 +0100
+++ b/web/formwidgets.py	Tue Mar 19 12:24:40 2013 +0100
@@ -842,7 +842,7 @@
 
     def _get_url(self, entity, field):
         fname = self.autocomplete_initfunc
-        return entity._cw.build_url('json', fname=fname, mode='remote',
+        return entity._cw.build_url('ajax', fname=fname, mode='remote',
                                     pageid=entity._cw.pageid)