diff --git a/lucene/core/src/java/org/apache/lucene/util/packed/AppendingLongBuffer.java b/lucene/core/src/java/org/apache/lucene/util/packed/AppendingLongBuffer.java
index 0b5f00c9d81..fa24cbceb44 100644
--- a/lucene/core/src/java/org/apache/lucene/util/packed/AppendingLongBuffer.java
+++ b/lucene/core/src/java/org/apache/lucene/util/packed/AppendingLongBuffer.java
@@ -25,6 +25,7 @@ import org.apache.lucene.util.RamUsageEstimator;
 /**
  * Utility class to buffer a list of signed longs in memory. This class only
  * supports appending.
+ * @lucene.internal
  */
 public class AppendingLongBuffer {