diff --git a/mongodb/src/main/java/org/springframework/data/examples/mongodb/shop/OrderRepositoryImpl.java b/mongodb/src/main/java/org/springframework/data/examples/mongodb/shop/OrderRepositoryImpl.java
index c67c2fb4..868eff03 100644
--- a/mongodb/src/main/java/org/springframework/data/examples/mongodb/shop/OrderRepositoryImpl.java
+++ b/mongodb/src/main/java/org/springframework/data/examples/mongodb/shop/OrderRepositoryImpl.java
@@ -34,7 +34,7 @@ import org.springframework.data.mongodb.core.aggregation.AggregationResults;
 @RequiredArgsConstructor(onConstructor = @__(@Autowired))
 class OrderRepositoryImpl implements OrderRepositoryCustom {
 
-	private MongoOperations operations;
+	private final MongoOperations operations;
 
 	private double taxRate = 0.19;