diff --git a/sale.py b/sale.py
index 492c068276..b946d351ac 100644
--- a/sale.py
+++ b/sale.py
@@ -91,7 +91,7 @@ class Line(metaclass=PoolMeta):
                         for l in invoice_lines)):
                 return
 
-        date = self.shipping_date
+        date = self.shipping_date or today
         if date <= today:
             date = today
         else: