diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index a17db039415..37cd831ffd4 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -435,6 +435,10 @@ Release 2.5.0 - UNRELEASED
     HDFS-6337. Setfacl testcase is failing due to dash character in username
     in TestAclCLI (umamahesh)
 
+    HDFS-5381. ExtendedBlock#hashCode should use both blockId and block pool ID    
+    (Benoy Antony via Colin Patrick McCabe)
+
+
 Release 2.4.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/ExtendedBlock.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/ExtendedBlock.java
index 3d8f3754922..27c1761ad26 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/ExtendedBlock.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/ExtendedBlock.java
@@ -112,7 +112,8 @@ public class ExtendedBlock {
   
   @Override // Object
   public int hashCode() {
-    return block.hashCode();
+    int result = 31 + poolId.hashCode();
+    return (31 * result + block.hashCode());
   }
   
   @Override // Object
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocol/TestExtendedBlock.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocol/TestExtendedBlock.java
index 4c117a992e8..10c1671b627 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocol/TestExtendedBlock.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocol/TestExtendedBlock.java
@@ -49,6 +49,26 @@ public class TestExtendedBlock {
         new ExtendedBlock(POOL_A, BLOCK_1_GS1),
         new ExtendedBlock(POOL_A, BLOCK_1_GS2));
   }
+  
+  @Test
+  public void testHashcode() {
+    
+    // Different pools, same block id -> different hashcode
+    assertNotEquals(
+        new ExtendedBlock(POOL_A, BLOCK_1_GS1).hashCode(),
+        new ExtendedBlock(POOL_B, BLOCK_1_GS1).hashCode());
+    
+    // Same pool, different block id -> different hashcode
+    assertNotEquals(
+        new ExtendedBlock(POOL_A, BLOCK_1_GS1).hashCode(),
+        new ExtendedBlock(POOL_A, BLOCK_2_GS1).hashCode());
+    
+    // Same block -> same hashcode
+    assertEquals(
+        new ExtendedBlock(POOL_A, BLOCK_1_GS1).hashCode(),
+        new ExtendedBlock(POOL_A, BLOCK_1_GS1).hashCode());
+
+  }
 
   private static void assertNotEquals(Object a, Object b) {
     assertFalse("expected not equal: '" + a + "' and '" + b + "'",