diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index 5f75d6f0c08..463c3362667 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -178,6 +178,8 @@ Release 0.23.1 - Unreleased
     MAPREDUCE-3547. Added a bunch of unit tests for the the RM/NM webservices.
     (Thomas Graves via acmurthy)
 
+    MAPREDUCE-3610. Remove use of the 'dfs.block.size' config for default block size fetching. Use FS#getDefaultBlocksize instead. (Sho Shimauchi via harsh)
+
   OPTIMIZATIONS
 
     MAPREDUCE-3567. Extraneous JobConf objects in AM heap. (Vinod Kumar
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/JobImpl.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/JobImpl.java
index 183f15156c5..f498590fdc7 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/JobImpl.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/JobImpl.java
@@ -858,8 +858,9 @@ public class JobImpl implements org.apache.hadoop.mapreduce.v2.app.job.Job,
     int sysMaxReduces = 1;
 
     long sysMaxBytes = conf.getLong(MRJobConfig.JOB_UBERTASK_MAXBYTES,
-        conf.getLong("dfs.block.size", 64*1024*1024));  //FIXME: this is
-    // wrong; get FS from [File?]InputFormat and default block size from that
+        fs.getDefaultBlockSize()); // FIXME: this is wrong; get FS from
+                                   // [File?]InputFormat and default block size
+                                   // from that
 
     long sysMemSizeForUberSlot =
         conf.getInt(MRJobConfig.MR_AM_VMEM_MB,
diff --git a/hadoop-mapreduce-project/src/test/mapred/org/apache/hadoop/mapreduce/lib/input/TestCombineFileInputFormat.java b/hadoop-mapreduce-project/src/test/mapred/org/apache/hadoop/mapreduce/lib/input/TestCombineFileInputFormat.java
index 4915be5f864..9369ffc7404 100644
--- a/hadoop-mapreduce-project/src/test/mapred/org/apache/hadoop/mapreduce/lib/input/TestCombineFileInputFormat.java
+++ b/hadoop-mapreduce-project/src/test/mapred/org/apache/hadoop/mapreduce/lib/input/TestCombineFileInputFormat.java
@@ -1144,7 +1144,7 @@ public class TestCombineFileInputFormat extends TestCase {
     if (!(fs instanceof DistributedFileSystem)) {
       throw new IOException("Wrong file system: " + fs.getClass().getName());
     }
-    int blockSize = conf.getInt("dfs.block.size", 128 * 1024 * 1024);
+    long blockSize = fs.getDefaultBlockSize();
 
     DummyInputFormat inFormat = new DummyInputFormat();
     for (int i = 0; i < args.length; i++) {