diff --git a/modules/purchase/purchase.py b/modules/purchase/purchase.py
index 6d9632d1db..e81b5437d1 100644
--- a/modules/purchase/purchase.py
+++ b/modules/purchase/purchase.py
@@ -2040,7 +2040,7 @@ class Line(sequence_ordered(), ModelSQL, ModelView):
         quantity = (
             self._get_move_quantity(move_type)
             - self._get_shipped_quantity(move_type))
-        if quantity < 0:
+        if self.unit.round(quantity) < 0:
             warning_name = Warning.format(
                 'check_move_quantity', [self])
             if Warning.check(warning_name):
diff --git a/modules/sale/sale.py b/modules/sale/sale.py
index 0db85d9aed..f2db1e048e 100644
--- a/modules/sale/sale.py
+++ b/modules/sale/sale.py
@@ -2167,7 +2167,7 @@ class SaleLine(TaxableMixin, sequence_ordered(), ModelSQL, ModelView):
         quantity = (
             self._get_move_quantity(move_type)
             - self._get_shipped_quantity(move_type))
-        if quantity < 0:
+        if self.unit.round(quantity) < 0:
             warning_name = Warning.format(
                 'check_move_quantity', [self])
             if Warning.check(warning_name):