diff --git a/inventory.py b/inventory.py
index 6a1e4519ea..dfcf8a3ea2 100644
--- a/inventory.py
+++ b/inventory.py
@@ -216,8 +216,12 @@ class CompleteInventory(Wizard):
         for inventory in inventories:
             products = [line.product.id for line in inventory.lines]
             for (product, uom, qty) in indexed_data[inventory.location.id]:
+                # Skip products already in the inventory:
                 if product in products:
                     continue
+                if qty <= 0.0:
+                    qty = 0
+                if product in products: continue
                 line_obj.create(
                     cursor, user,
                     {'product': product,