diff --git a/addons/hr_timesheet_sheet/hr_timesheet_sheet.py b/addons/hr_timesheet_sheet/hr_timesheet_sheet.py
index b7d395ac2e0..b6078648147 100644
--- a/addons/hr_timesheet_sheet/hr_timesheet_sheet.py
+++ b/addons/hr_timesheet_sheet/hr_timesheet_sheet.py
@@ -364,7 +364,7 @@ class hr_timesheet_line(osv.osv):
                 res[line_id] = False
         return res
 
-    def _sheet_search(self, cursor, user, obj, name, args, context):
+    def _sheet_search(self, cursor, user, obj, name, args, context=None):
         if not len(args):
             return []
         sheet_obj = self.pool.get('hr_timesheet_sheet.sheet')
@@ -482,7 +482,7 @@ class hr_attendance(osv.osv):
                 res[line_id] = False
         return res
 
-    def _sheet_search(self, cursor, user, obj, name, args, context={}):
+    def _sheet_search(self, cursor, user, obj, name, args, context=None):
         if not len(args):
             return []
         sheet_obj = self.pool.get('hr_timesheet_sheet.sheet')