diff --git a/CHANGES.txt b/CHANGES.txt
index ab85ea9e55..63a97d40f7 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -8,6 +8,7 @@
  * Add SnapshotBeforeCompaction configuration option (CASSANDRA-426)
  * Fix compaction abort under insufficient disk space (CASSANDRA-473)
  * Fix reading subcolumn slice from tombstoned CF (CASSANDRA-484)
+ * Fix race condition in RVH causing occasional NPE (CASSANDRA-478)
 
 
 0.4.0
diff --git a/src/java/org/apache/cassandra/service/ConsistencyManager.java b/src/java/org/apache/cassandra/service/ConsistencyManager.java
index 69c3296bdd..226144952a 100644
--- a/src/java/org/apache/cassandra/service/ConsistencyManager.java
+++ b/src/java/org/apache/cassandra/service/ConsistencyManager.java
@@ -48,7 +48,7 @@ class ConsistencyManager implements Runnable
 	{
 		List<Message> responses_ = new ArrayList<Message>();
 		
-		public void response(Message msg)
+		public synchronized void response(Message msg)
 		{
 			responses_.add(msg);
 			if ( responses_.size() == ConsistencyManager.this.replicas_.size() )