diff --git a/hr_timesheet_sheet/models/hr_timesheet_sheet.py b/hr_timesheet_sheet/models/hr_timesheet_sheet.py
index ef5a6ce56d..4ea586a81d 100644
--- a/hr_timesheet_sheet/models/hr_timesheet_sheet.py
+++ b/hr_timesheet_sheet/models/hr_timesheet_sheet.py
@@ -285,17 +285,16 @@ def _compute_line_ids(self):
 
     def _create_data_matrix_lines(self, data_matrix):
         self.ensure_one()
-        lines = self.env['hr_timesheet.sheet.line']
+        vals_list = []
         for item in data_matrix:
-            lines |= self.env['hr_timesheet.sheet.line'].create(
-                self._get_default_sheet_line(
-                    date=item[0],
-                    project=item[1],
-                    task=item[2],
-                    unit_amount=data_matrix[item]['unit_amount']
-                ))
+            vals_list += [self._get_default_sheet_line(
+                date=item[0],
+                project=item[1],
+                task=item[2],
+                unit_amount=data_matrix[item]['unit_amount']
+            )]
             self.clean_timesheets(data_matrix[item]['timesheets'])
-        return lines
+        return self.env['hr_timesheet.sheet.line'].create(vals_list)
 
     @api.onchange('date_start', 'date_end', 'employee_id')
     def _onchange_dates(self):