diff --git a/impl/shim/mapreduce/src/main/java/org/pentaho/big/data/impl/shim/mapreduce/FutureMapReduceJobSimpleRunnable.java b/impl/shim/mapreduce/src/main/java/org/pentaho/big/data/impl/shim/mapreduce/FutureMapReduceJobSimpleRunnable.java
index 896fe70e7ec..1669506a70e 100644
--- a/impl/shim/mapreduce/src/main/java/org/pentaho/big/data/impl/shim/mapreduce/FutureMapReduceJobSimpleRunnable.java
+++ b/impl/shim/mapreduce/src/main/java/org/pentaho/big/data/impl/shim/mapreduce/FutureMapReduceJobSimpleRunnable.java
@@ -94,7 +94,7 @@ protected void executeMainMethod( Class<?> clazz, String commandLineArgs )
       Method mainMethod = clazz.getMethod( "main", new Class[] { String[].class } );
       Object[] args =
         ( commandLineArgs != null ) ? new Object[] { commandLineArgs.split( " " ) } : new Object[] { new String[ 0 ] };
-      mainMethod.invoke( null, args );
+      mainMethod.invoke( clazz.newInstance(), args );
     } finally {
       Thread.currentThread().setContextClassLoader( cl );
     }
diff --git a/impl/shim/mapreduce/src/main/java/org/pentaho/big/data/impl/shim/mapreduce/MapReduceServiceImpl.java b/impl/shim/mapreduce/src/main/java/org/pentaho/big/data/impl/shim/mapreduce/MapReduceServiceImpl.java
index 9951a74fca5..4b07345c07a 100644
--- a/impl/shim/mapreduce/src/main/java/org/pentaho/big/data/impl/shim/mapreduce/MapReduceServiceImpl.java
+++ b/impl/shim/mapreduce/src/main/java/org/pentaho/big/data/impl/shim/mapreduce/MapReduceServiceImpl.java
@@ -153,10 +153,10 @@ Class<?> locateDriverClass( String driverClass, final URL resolvedJarUrl, final
     throws MapReduceExecutionException {
     try {
       if ( Utils.isEmpty( driverClass ) ) {
+        List<Class<?>> mainClasses =
+            jarUtility.getClassesInJarWithMain( resolvedJarUrl.toExternalForm(), shim.getClass().getClassLoader() );   
         Class<?> mainClass = jarUtility.getMainClassFromManifest( resolvedJarUrl, shim.getClass().getClassLoader() );
         if ( mainClass == null ) {
-          List<Class<?>> mainClasses =
-            jarUtility.getClassesInJarWithMain( resolvedJarUrl.toExternalForm(), shim.getClass().getClassLoader() );
           if ( mainClasses.size() == 1 ) {
             return mainClasses.get( 0 );
           } else if ( mainClasses.isEmpty() ) {