diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 40ee26e9bc..2267b0ac6e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -468,6 +468,9 @@ Trunk (Unreleased)
     HDFS-5659. dfsadmin -report doesn't output cache information properly.
     (wang)
 
+    HDFS-5705. TestSecondaryNameNodeUpgrade#testChangeNsIDFails may fail due
+    to ConcurrentModificationException. (Ted Yu via brandonli)
+
   BREAKDOWN OF HDFS-2832 SUBTASKS AND RELATED JIRAS
 
     HDFS-4985. Add storage type to the protocol and expose it in block report
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsVolumeImpl.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsVolumeImpl.java
index 9e5b0ebee4..795fab1f3a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsVolumeImpl.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsVolumeImpl.java
@@ -19,10 +19,10 @@
 
 import java.io.File;
 import java.io.IOException;
-import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Executor;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ThreadFactory;
@@ -54,7 +54,7 @@ class FsVolumeImpl implements FsVolumeSpi {
   private final String storageID;
   private final StorageType storageType;
   private final Map<String, BlockPoolSlice> bpSlices
-      = new HashMap<String, BlockPoolSlice>();
+      = new ConcurrentHashMap<String, BlockPoolSlice>();
   private final File currentDir;    // <StorageDirectory>/current
   private final DF usage;           
   private final long reserved;