diff --git a/spring-batch-infrastructure/src/main/java/org/springframework/batch/support/transaction/TransactionAwareBufferedWriter.java b/spring-batch-infrastructure/src/main/java/org/springframework/batch/support/transaction/TransactionAwareBufferedWriter.java
index 8ac34f8a8..1ccbd33c4 100644
--- a/spring-batch-infrastructure/src/main/java/org/springframework/batch/support/transaction/TransactionAwareBufferedWriter.java
+++ b/spring-batch-infrastructure/src/main/java/org/springframework/batch/support/transaction/TransactionAwareBufferedWriter.java
@@ -35,7 +35,7 @@ public class TransactionAwareBufferedWriter extends Writer {
 
 	private static final String BUFFER_KEY_PREFIX = TransactionAwareBufferedWriter.class.getName() + ".BUFFER_KEY";
 
-	private String bufferKey;
+	private final String bufferKey;
 
 	private Writer writer;