diff --git a/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala b/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala
index 662ec5fbed4537780a84b479288b90f4c6e0d573..5995d6df97c150cf8e3e174e8bab31f9f59d6928 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala
@@ -1113,7 +1113,10 @@ private[spark] object SerDe extends Serializable {
       iter.flatMap { row =>
         val obj = unpickle.loads(row)
         if (batched) {
-          obj.asInstanceOf[JArrayList[_]].asScala
+          obj match {
+            case list: JArrayList[_] => list.asScala
+            case arr: Array[_] => arr
+          }
         } else {
           Seq(obj)
         }
diff --git a/python/pyspark/mllib/tests.py b/python/pyspark/mllib/tests.py
index 893fc6f491ab32c56caaebb5c389142140769e76..6e9c68ec8a5c169a109105448aa22cec2842b548 100644
--- a/python/pyspark/mllib/tests.py
+++ b/python/pyspark/mllib/tests.py
@@ -36,6 +36,7 @@ if sys.version_info[:2] <= (2, 6):
 else:
     import unittest
 
+from pyspark.mllib.common import _to_java_object_rdd
 from pyspark.mllib.linalg import Vector, SparseVector, DenseVector, VectorUDT, _convert_to_vector,\
     DenseMatrix, Vectors, Matrices
 from pyspark.mllib.regression import LabeledPoint
@@ -641,6 +642,13 @@ class FeatureTest(PySparkTestCase):
         idf = model.idf()
         self.assertEqual(len(idf), 11)
 
+
+class SerDeTest(PySparkTestCase):
+    def test_to_java_object_rdd(self):  # SPARK-6660
+        data = RandomRDDs.uniformRDD(self.sc, 10, 5, seed=0L)
+        self.assertEqual(_to_java_object_rdd(data).count(), 10)
+
+
 if __name__ == "__main__":
     if not _have_scipy:
         print "NOTE: Skipping SciPy tests as it does not seem to be installed"