diff --git a/sale.py b/sale.py
index 6a2ef48fd5..538bdf1035 100644
--- a/sale.py
+++ b/sale.py
@@ -186,7 +186,8 @@ class Sale(metaclass=PoolMeta):
     @Workflow.transition('cancel')
     def cancel(cls, sales):
         for sale in sales:
-            sale.coupons = []
+            if sale.coupons:
+                sale.coupons = []
         cls.save(sales)
         super(Sale, cls).cancel(sales)