diff --git a/product_contract_variable_quantity/models/product_template.py b/product_contract_variable_quantity/models/product_template.py
index ad039bf2..a99ae9aa 100644
--- a/product_contract_variable_quantity/models/product_template.py
+++ b/product_contract_variable_quantity/models/product_template.py
@@ -25,7 +25,8 @@ class ProductTemplate(models.Model):
         """ Clear the relation to contract_template_id when downgrading
         product from contract
         """
-        super(ProductTemplate, self)._change_is_contract()
+        res = super(ProductTemplate, self)._change_is_contract()
         if not self.is_contract:
             self.qty_type = False
             self.qty_formula_id = False
+        return res
diff --git a/product_contract_variable_quantity/models/sale_order_line.py b/product_contract_variable_quantity/models/sale_order_line.py
index 2f211edb..d66b9874 100644
--- a/product_contract_variable_quantity/models/sale_order_line.py
+++ b/product_contract_variable_quantity/models/sale_order_line.py
@@ -25,11 +25,12 @@ class SaleOrderLine(models.Model):
 
     @api.onchange('product_id')
     def onchange_product(self):
-        super(SaleOrderLine, self).onchange_product()
+        res = super(SaleOrderLine, self).onchange_product()
         for rec in self:
             if rec.product_id.is_contract:
                 rec.qty_type = rec.product_id.qty_type
                 rec.qty_formula_id = rec.product_id.qty_formula_id
+        return res
 
     @api.multi
     def _prepare_contract_line_values(