diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 1e446de351..7c1685ccc9 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -270,6 +270,9 @@ Trunk (Unreleased)
     HDFS-4687. TestDelegationTokenForProxyUser#testWebHdfsDoAs is flaky with
     JDK7. (Andrew Wang via atm)
 
+    HDFS-4785. Concat operation does not remove concatenated files from
+    InodeMap. (suresh)
+
   BREAKDOWN OF HADOOP-8562 and HDFS-3602 SUBTASKS AND RELATED JIRAS
 
     HDFS-4145. Merge hdfs cmd line scripts from branch-1-win. (David Lao,
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
index 8e3a74bb0d..aa7bd609c6 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
@@ -971,6 +971,7 @@ public void unprotectedConcat(String target, String [] srcs, long timestamp)
       
       nodeToRemove.setBlocks(null);
       trgParent.removeChild(nodeToRemove);
+      inodeMap.remove(nodeToRemove);
       count++;
     }
     
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestINodeFile.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestINodeFile.java
index ba1c968fce..01003a6671 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestINodeFile.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestINodeFile.java
@@ -451,8 +451,27 @@ public void testInodeId() throws IOException {
       assertTrue(fs.delete(renamedPath, true));
       inodeCount -= 2;
       assertEquals(inodeCount, fsn.dir.getInodeMapSize());
+      
+      // Create and concat /test/file1 /test/file2
+      // Create /test1/file1 and /test1/file2
+      String file1 = "/test1/file1";
+      String file2 = "/test1/file2";
+      DFSTestUtil.createFile(fs, new Path(file1), 512, (short) 1, 0);
+      DFSTestUtil.createFile(fs, new Path(file2), 512, (short) 1, 0);
+      inodeCount += 3; // test1, file1 and file2 are created
+      expectedLastInodeId += 3;
+      assertEquals(inodeCount, fsn.dir.getInodeMapSize());
+      assertEquals(expectedLastInodeId, fsn.getLastInodeId());
+      // Concat the /test1/file1 /test1/file2 into /test1/file2
+      nnrpc.concat(file2, new String[] {file1});
+      inodeCount--; // file1 and file2 are concatenated to file2
+      assertEquals(inodeCount, fsn.dir.getInodeMapSize());
+      assertEquals(expectedLastInodeId, fsn.getLastInodeId());
+      assertTrue(fs.delete(new Path("/test1"), true));
+      inodeCount -= 2; // test1 and file2 is deleted
+      assertEquals(inodeCount, fsn.dir.getInodeMapSize());
 
-      // Make sure empty editlog can be handled
+      // Make sure editlog is loaded correctly 
       cluster.restartNameNode();
       cluster.waitActive();
       fsn = cluster.getNamesystem();