diff --git a/addons/stock/models/stock_move.py b/addons/stock/models/stock_move.py
index c30932f69cb..2890244f906 100644
--- a/addons/stock/models/stock_move.py
+++ b/addons/stock/models/stock_move.py
@@ -481,6 +481,7 @@ class StockMove(models.Model):
                     move_line_vals = self._prepare_move_line_vals(quantity=0)
                     move_line_vals['lot_id'] = lot.id
                     move_line_vals['lot_name'] = lot.name
+                    move_line_vals['product_uom_id'] = move.product_id.uom_id.id
                     move_line_vals['qty_done'] = 1
                     move_lines_commands.append((0, 0, move_line_vals))
             move.write({'move_line_ids': move_lines_commands})
@@ -851,6 +852,9 @@ class StockMove(models.Model):
 
     @api.onchange('lot_ids')
     def _onchange_lot_ids(self):
+        quantity_done = sum(ml.product_uom_id._compute_quantity(ml.qty_done, self.product_uom) for ml in self.move_line_ids.filtered(lambda ml: not ml.lot_id and ml.lot_name))
+        quantity_done += self.product_id.uom_id._compute_quantity(len(self.lot_ids), self.product_uom)
+        self.update({'quantity_done': quantity_done})
         used_lots = self.env['stock.move.line'].search([
             ('company_id', '=', self.company_id.id),
             ('product_id', '=', self.product_id.id),
@@ -858,15 +862,6 @@ class StockMove(models.Model):
             ('move_id', '!=', self._origin.id),
             ('state', '!=', 'cancel')
         ])
-
-        counter = self.env['stock.move.line'].search_count([
-            ('company_id', '=', self.company_id.id),
-            ('product_id', '=', self.product_id.id),
-            ('move_id', '=', self._origin.id),
-            ('lot_id', '=', False),
-            ('lot_name', '!=', False),
-        ])
-        self.update({'quantity_done': len(self.lot_ids) + counter})
         if used_lots:
             return {
                 'warning': {'title': _('Warning'), 'message': _('Existing Serial numbers (%s). Please correct the serial numbers encoded.') % ','.join(used_lots.lot_id.mapped('display_name'))}
diff --git a/addons/stock/tests/test_move2.py b/addons/stock/tests/test_move2.py
index 308ca0dbf5b..54be08e6d91 100644
--- a/addons/stock/tests/test_move2.py
+++ b/addons/stock/tests/test_move2.py
@@ -2815,3 +2815,17 @@ class TestAutoAssign(TestStockCommon):
         self.assertEqual(move.quantity_done, 3.0)
         move.lot_ids = [(3, lot2.id)]
         self.assertEqual(move.quantity_done, 2.0)
+
+        self.uom_dozen = self.env.ref('uom.product_uom_dozen')
+        move = self.env['stock.move'].create({
+            'name': 'TestReceiveDozen',
+            'location_id': self.supplier_location.id,
+            'location_dest_id': self.stock_location.id,
+            'product_id': self.product_serial.id,
+            'product_uom': self.uom_dozen.id,
+            'picking_type_id': self.env.ref('stock.picking_type_in').id,
+        })
+        move.lot_ids = [(4, lot1.id)]
+        move.lot_ids = [(4, lot2.id)]
+        move.lot_ids = [(4, lot3.id)]
+        self.assertEqual(move.quantity_done, 3.0/12.0)