diff --git a/addons/stock/models/stock_move.py b/addons/stock/models/stock_move.py
index 2449d4ce0fd..4dafe149b2b 100644
--- a/addons/stock/models/stock_move.py
+++ b/addons/stock/models/stock_move.py
@@ -775,22 +775,22 @@ class StockMove(models.Model):
             .filtered(lambda move: move.state not in ['cancel', 'done'])\
             .sorted(key=lambda move: (sort_map.get(move.state, 0), move.product_uom_qty))
         # The picking should be the same for all moves.
-        if moves_todo[0].picking_id and moves_todo[0].picking_id.move_type == 'one':
+        if moves_todo[:1].picking_id and moves_todo[:1].picking_id.move_type == 'one':
             most_important_move = moves_todo[0]
             if most_important_move.state == 'confirmed':
                 return 'confirmed' if most_important_move.product_uom_qty else 'assigned'
             elif most_important_move.state == 'partially_available':
                 return 'confirmed'
             else:
-                return moves_todo[0].state or 'draft'
-        elif moves_todo[0].state != 'assigned' and any(move.state in ['assigned', 'partially_available'] for move in moves_todo):
+                return moves_todo[:1].state or 'draft'
+        elif moves_todo[:1].state != 'assigned' and any(move.state in ['assigned', 'partially_available'] for move in moves_todo):
             return 'partially_available'
         else:
-            least_important_move = moves_todo[-1]
+            least_important_move = moves_todo[-1:]
             if least_important_move.state == 'confirmed' and least_important_move.product_uom_qty == 0:
                 return 'assigned'
             else:
-                return moves_todo[-1].state or 'draft'
+                return moves_todo[-1:].state or 'draft'
 
     @api.onchange('product_id')
     def onchange_product_id(self):