diff --git a/CHANGES.txt b/CHANGES.txt
index 7bdcda5023..20d94bd4e6 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,4 +1,5 @@
 4.0.15
+ * Ensure thread-safety for CommitLogArchiver in CommitLog (CASSANDRA-19960)
  * Fix text containing "/*" being interpreted as multiline comment in cqlsh (CASSANDRA-17667)
  * Fix indexing of a frozen collection that is the clustering key and reversed (CASSANDRA-19889)
  * Emit error when altering a table with non-frozen UDTs with nested non-frozen collections the same way as done upon table creation (CASSANDRA-19925)
diff --git a/src/java/org/apache/cassandra/db/commitlog/CommitLog.java b/src/java/org/apache/cassandra/db/commitlog/CommitLog.java
index 214f24a049..0324c13c94 100644
--- a/src/java/org/apache/cassandra/db/commitlog/CommitLog.java
+++ b/src/java/org/apache/cassandra/db/commitlog/CommitLog.java
@@ -77,7 +77,7 @@ public class CommitLog implements CommitLogMBean
 
     final public AbstractCommitLogSegmentManager segmentManager;
 
-    public CommitLogArchiver archiver;
+    public volatile CommitLogArchiver archiver;
     public final CommitLogMetrics metrics;
     final AbstractCommitLogService executor;