diff --git a/core/src/main/scala/kafka/log/s3/operator/DefaultS3Operator.java b/core/src/main/scala/kafka/log/s3/operator/DefaultS3Operator.java
index b34b432299..a62d9e8706 100644
--- a/core/src/main/scala/kafka/log/s3/operator/DefaultS3Operator.java
+++ b/core/src/main/scala/kafka/log/s3/operator/DefaultS3Operator.java
@@ -399,7 +399,7 @@ public CompletableFuture<Void> close() {
             // upload the cached buf anyway. Note that the last part can be smaller than minPartSize.
             if (cachedBuf != null) {
                 handleWriteFuturePart(cachedBufLastAddCf, cachedBuf, System.nanoTime());
-                cachedBuf = null;
+                clearCache();
             }
 
             OBJECT_INTO_CLOSE_COST.update(System.nanoTime() - start);