diff --git a/purchase_usability/models/purchase_order.py b/purchase_usability/models/purchase_order.py
index c359736..df0c462 100644
--- a/purchase_usability/models/purchase_order.py
+++ b/purchase_usability/models/purchase_order.py
@@ -2,8 +2,9 @@
 # @author Alexis de Lattre <alexis.delattre@akretion.com>
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
-from odoo import api, fields, models
-from odoo.tools.misc import formatLang
+from odoo import api, fields, models, _
+from odoo.tools.misc import format_datetime, format_amount
+from odoo.tools import float_compare
 
 
 class PurchaseOrder(models.Model):
@@ -25,7 +26,7 @@ class PurchaseOrder(models.Model):
             order.delivery_partner_id = order.dest_address_id
 
     # Re-write native name_get() to use amount_untaxed instead of amount_total
-    @api.depends('name', 'partner_ref')
+    @api.depends('name', 'partner_ref', 'amount_untaxed')
     def name_get(self):
         result = []
         for po in self:
@@ -33,8 +34,8 @@ class PurchaseOrder(models.Model):
             if po.partner_ref:
                 name += ' (' + po.partner_ref + ')'
             if self.env.context.get('show_total_amount') and po.amount_untaxed:
-                name += ': ' + formatLang(
-                    self.env, po.amount_untaxed, currency_obj=po.currency_id)
+                name += ': ' + format_amount(
+                    self.env, po.amount_untaxed, po.currency_id)
             result.append((po.id, name))
         return result
 
@@ -72,7 +73,8 @@ class PurchaseOrderLine(models.Model):
     _inherit = 'purchase.order.line'
 
     # for optional display in tree view
-    product_barcode = fields.Char(related='product_id.barcode', string="Product Barcode")
+    product_barcode = fields.Char(
+        related='product_id.barcode', string="Product Barcode")
     product_supplier_code = fields.Char(
         compute='_compute_product_supplier_code', string='Vendor Product Code')
 
@@ -98,3 +100,41 @@ class PurchaseOrderLine(models.Model):
         if no_product_code_param and no_product_code_param == 'True':
             product_lang = product_lang.with_context(display_default_code=False)
         return super()._get_product_purchase_description(product_lang)
+
+    @api.onchange('product_qty', 'product_uom')
+    def _onchange_quantity(self):
+        # When the user has manually set a price and/or planned_date
+        # he is often upset when Odoo changes it when he changes the qty
+        # So we add a warning...
+        res = {}
+        old_price = self.price_unit
+        old_date_planned = self.date_planned
+        super()._onchange_quantity()
+        new_price = self.price_unit
+        new_date_planned = self.date_planned
+        prec = self.env['decimal.precision'].precision_get('Product Price')
+        price_compare = float_compare(old_price, new_price, precision_digits=prec)
+        if price_compare or old_date_planned != new_date_planned:
+            res['warning'] = {
+                'title': _('Updates'),
+                'message': _(
+                    "Due to the update of the ordered quantity on line '%s', "
+                    "the following data has been updated using the supplier info "
+                    "of the product:"
+                    ) % self.name
+                }
+            if price_compare:
+                res['warning']['message'] += _(
+                    "\nOld price: %s\nNew price: %s") % (
+                        format_amount(
+                            self.env, old_price, self.order_id.currency_id),
+                        format_amount(
+                            self.env, new_price, self.order_id.currency_id))
+
+            if old_date_planned != new_date_planned:
+                res['warning']['message'] += _(
+                    "\nOld delivery date: %s\nNew delivery date: %s") % (
+                        format_datetime(self.env, old_date_planned),
+                        format_datetime(self.env, new_date_planned),
+                    )
+        return res