diff --git a/product/ERP5/Document/SimulationMovement.py b/product/ERP5/Document/SimulationMovement.py
index cfcc3c9ad4057843cba58e2885d47efdefe3e518..4460026d6c16ef74770b74f9d32f70cef16fa895 100644
--- a/product/ERP5/Document/SimulationMovement.py
+++ b/product/ERP5/Document/SimulationMovement.py
@@ -417,7 +417,7 @@ class SimulationMovement(Movement):
     """
       Returns the quantity of related delivery(s)
     """
-    quantity = None
+    quantity = 0.0
     delivery_movement = self.getDeliveryValue()
     if delivery_movement is not None:
       quantity = delivery_movement.getQuantity()