diff --git a/addons/delivery/delivery.py b/addons/delivery/delivery.py
index c240ab19f6e..64b6597798d 100644
--- a/addons/delivery/delivery.py
+++ b/addons/delivery/delivery.py
@@ -112,10 +112,10 @@ class delivery_carrier(osv.osv):
             # not using advanced pricing per destination: override grid
             grid_id = grid_pool.search(cr, uid, [('carrier_id', '=', record.id)], context=context)
 
-            if grid_id and not (record.normal_price or record.free_if_more_than):
+            if grid_id and not (record.normal_price is not False or record.free_if_more_than):
                 grid_pool.unlink(cr, uid, grid_id, context=context)
 
-            if not (record.normal_price or record.free_if_more_than):
+            if not (record.normal_price is not False or record.free_if_more_than):
                 continue
 
             if not grid_id:
@@ -142,7 +142,7 @@ class delivery_carrier(osv.osv):
                     'list_price': 0.0,
                 }
                 grid_line_pool.create(cr, uid, line_data, context=context)
-            if record.normal_price:
+            if record.normal_price is not False:
                 line_data = {
                     'grid_id': grid_id and grid_id[0],
                     'name': _('Default price'),