diff --git a/quality_control/models/quality.py b/quality_control/models/quality.py
index f3a4315f..1ab0e862 100644
--- a/quality_control/models/quality.py
+++ b/quality_control/models/quality.py
@@ -735,8 +735,9 @@ class QualityCheck(models.Model):
     def _compute_qty_to_test(self):
         for qc in self:
             if qc.is_lot_tested_fractionally:
+                rounding = qc.product_id.uom_id.rounding if qc.product_id.uom_id else 0.01
                 qc.qty_to_test = float_round(qc.qty_line * qc.testing_percentage_within_lot / 100,
-                                             precision_rounding=self.product_id.uom_id.rounding, rounding_method="UP")
+                                             precision_rounding=rounding, rounding_method="UP")
             else:
                 qc.qty_to_test = qc.qty_line