diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index c103b4c0e9b..731c4ef986a 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -92,6 +92,9 @@ Release 2.4.0 - UNRELEASED
     MAPREDUCE-5794. SliveMapper always uses default FileSystem. (szetszwo via
     Arpit Agarwal)
 
+    MAPREDUCE-5751. MR app master fails to start in some cases if
+    mapreduce.job.classloader is true (Sangjin Lee via jlowe)
+
 Release 2.3.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/MRAppMaster.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/MRAppMaster.java
index ac69eb04aee..30f5973bd53 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/MRAppMaster.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/MRAppMaster.java
@@ -1066,6 +1066,8 @@ public class MRAppMaster extends CompositeService {
     //start all the components
     super.serviceStart();
 
+    // set job classloader if configured
+    MRApps.setJobClassLoader(getConfig());
     // All components have started, start the job.
     startJobs();
   }
@@ -1376,8 +1378,6 @@ public class MRAppMaster extends CompositeService {
       // SIGTERM I have a chance to write out the job history. I'll be closing
       // the objects myself.
       conf.setBoolean("fs.automatic.close", false);
-      // set job classloader if configured
-      MRApps.setJobClassLoader(conf);
       initAndStartAppMaster(appMaster, conf, jobUserName);
     } catch (Throwable t) {
       LOG.fatal("Error starting MRAppMaster", t);