diff --git a/src/purchase/models.py b/src/purchase/models.py
index a274c13..c8f6e46 100644
--- a/src/purchase/models.py
+++ b/src/purchase/models.py
@@ -50,7 +50,6 @@ class PaymentMethod(Model):
     def __str__(self):
         return self.name
 
-    @property
     def natural_key(self):
         return (self.name,)
 
@@ -99,7 +98,6 @@ class Product(Model):
     def __str__(self):
         return self.name
 
-    @property
     def natural_key(self):
         return (self.name,)