diff --git a/bin/osv/orm.py b/bin/osv/orm.py
index 29eab99a7d1..adf1d293790 100644
--- a/bin/osv/orm.py
+++ b/bin/osv/orm.py
@@ -2013,7 +2013,8 @@ class orm(orm_template):
 
         for d in data:
             d['__domain'] = [(groupby,'=',alldata[d['id']][groupby] or False)] + domain
-            d['__context'] = {'group_by':groupby_list[1:]}
+            if not isinstance(groupby_list,(str, unicode)):
+                d['__context'] = {'group_by':groupby_list[1:]}
             if fget.has_key(groupby):
                 if d[groupby] and fget[groupby]['type'] in ('date','datetime'):
                    dt = datetime.datetime.strptime(alldata[d['id']][groupby][:7],'%Y-%m')