diff --git a/purchase.py b/purchase.py
index 5f08b2b88e..c54ac1b624 100644
--- a/purchase.py
+++ b/purchase.py
@@ -15,5 +15,5 @@ class Line(metaclass=PoolMeta):
         states={
             'invisible': Eval('type') != 'line',
             },
-        depends=['type'],
+        depends=['type', 'purchase'],
         help="Add to the cost of the work effort.")