diff --git a/CHANGES.txt b/CHANGES.txt
index 14b43e563b..d1d10301d8 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,4 +1,5 @@
 2.0.9
+ * Fix NPE in StreamTransferTask.createMessageForRetry() (CASSANDRA-7323)
  * Add conditional CREATE/DROP USER support (CASSANDRA-7264)
  * Swap local and global default read repair chances (CASSANDRA-7320)
  * Add missing iso8601 patterns for date strings (CASSANDRA-6973)
diff --git a/src/java/org/apache/cassandra/streaming/StreamTransferTask.java b/src/java/org/apache/cassandra/streaming/StreamTransferTask.java
index 7d0cc87e81..a543d01e8d 100644
--- a/src/java/org/apache/cassandra/streaming/StreamTransferTask.java
+++ b/src/java/org/apache/cassandra/streaming/StreamTransferTask.java
@@ -99,11 +99,12 @@ public class StreamTransferTask extends StreamTask
         return new ArrayList<>(files.values());
     }
 
-    public OutgoingFileMessage createMessageForRetry(int sequenceNumber)
+    public synchronized OutgoingFileMessage createMessageForRetry(int sequenceNumber)
     {
         // remove previous time out task to be rescheduled later
         ScheduledFuture future = timeoutTasks.get(sequenceNumber);
-        future.cancel(false);
+        if (future != null)
+            future.cancel(false);
         return files.get(sequenceNumber);
     }