diff --git a/ssi_stock/models/stock_production_lot.py b/ssi_stock/models/stock_production_lot.py
index 910e9a8..2178bf4 100644
--- a/ssi_stock/models/stock_production_lot.py
+++ b/ssi_stock/models/stock_production_lot.py
@@ -63,6 +63,6 @@ def _compute_stock_move_line(self):
     )
     serial_number_acquisition_value = fields.Float(
         string="Acquisition Value",
-        related="last_stock_move_line_id.move_id.price_unit",
+        related="first_stock_move_line_id.move_id.price_unit",
         store=True,
     )