diff --git a/product/ERP5/MovementGroup.py b/product/ERP5/MovementGroup.py
index 9292e71ca4001d9f23131ee644ed1699f50db471..5aec7d0f573780e22e348c0be8d80f850b3db4ae 100755
--- a/product/ERP5/MovementGroup.py
+++ b/product/ERP5/MovementGroup.py
@@ -308,7 +308,9 @@ class QuantitySignMovementGroup(RootMovementGroup):
   def __init__(self, movement, **kw):
     RootMovementGroup.__init__(self, movement=movement, **kw)
     quantity = movement.getQuantity()
-    if quantity >= 0:
+    if quantity == 0:
+      self.sign = 0
+    elif quantity > 0:
       self.sign = 1
     else:
       self.sign = -1
@@ -316,13 +318,13 @@ class QuantitySignMovementGroup(RootMovementGroup):
 
   def test(self, movement):
     quantity = movement.getQuantity()
-    if quantity >= 0:
+    if quantity == 0 or self.sign == 0 :
+      return 1
+    if quantity > 0:
       sign = 1
     else:
       sign = -1
-    if self.sign == sign:
-      return 1
-    return 0
+    return self.sign == sign
 
 allow_class(QuantitySignMovementGroup)