diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 1eb06392507..a3926199d19 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -266,6 +266,10 @@ Release 2.0.3-alpha - Unreleased
     HDFS-4216. Do not ignore QuotaExceededException when adding symlinks.
     (szetszwo)
 
+    HDFS-4242. Map.Entry is incorrectly used in LeaseManager since the behavior
+    of it is undefined after the iteration or modifications of the map.
+    (szetszwo)
+
 Release 2.0.2-alpha - 2012-09-07 
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/LeaseManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/LeaseManager.java
index fd1cbfcc571..b1764b7d3cb 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/LeaseManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/LeaseManager.java
@@ -17,9 +17,12 @@
  */
 package org.apache.hadoop.hdfs.server.namenode;
 
+import static org.apache.hadoop.util.Time.now;
+
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.SortedMap;
@@ -39,8 +42,6 @@ import org.apache.hadoop.util.Daemon;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 
-import static org.apache.hadoop.util.Time.now;
-
 /**
  * LeaseManager does the lease housekeeping for writing on files.   
  * This class also provides useful static methods for lease recovery.
@@ -340,7 +341,8 @@ public class LeaseManager {
     }
 
     final int len = overwrite.length();
-    for(Map.Entry<String, Lease> entry : findLeaseWithPrefixPath(src, sortedLeasesByPath)) {
+    for(Map.Entry<String, Lease> entry
+        : findLeaseWithPrefixPath(src, sortedLeasesByPath).entrySet()) {
       final String oldpath = entry.getKey();
       final Lease lease = entry.getValue();
       //overwrite must be a prefix of oldpath
@@ -355,7 +357,8 @@ public class LeaseManager {
   }
 
   synchronized void removeLeaseWithPrefixPath(String prefix) {
-    for(Map.Entry<String, Lease> entry : findLeaseWithPrefixPath(prefix, sortedLeasesByPath)) {
+    for(Map.Entry<String, Lease> entry
+        : findLeaseWithPrefixPath(prefix, sortedLeasesByPath).entrySet()) {
       if (LOG.isDebugEnabled()) {
         LOG.debug(LeaseManager.class.getSimpleName()
             + ".removeLeaseWithPrefixPath: entry=" + entry);
@@ -364,13 +367,13 @@ public class LeaseManager {
     }
   }
 
-  static private List<Map.Entry<String, Lease>> findLeaseWithPrefixPath(
+  static private Map<String, Lease> findLeaseWithPrefixPath(
       String prefix, SortedMap<String, Lease> path2lease) {
     if (LOG.isDebugEnabled()) {
       LOG.debug(LeaseManager.class.getSimpleName() + ".findLease: prefix=" + prefix);
     }
 
-    List<Map.Entry<String, Lease>> entries = new ArrayList<Map.Entry<String, Lease>>();
+    final Map<String, Lease> entries = new HashMap<String, Lease>();
     final int srclen = prefix.length();
 
     for(Map.Entry<String, Lease> entry : path2lease.tailMap(prefix).entrySet()) {
@@ -379,7 +382,7 @@ public class LeaseManager {
         return entries;
       }
       if (p.length() == srclen || p.charAt(srclen) == Path.SEPARATOR_CHAR) {
-        entries.add(entry);
+        entries.put(entry.getKey(), entry.getValue());
       }
     }
     return entries;