diff --git a/docs/mllib-feature-extraction.md b/docs/mllib-feature-extraction.md
index 764985d436..1f6ad8b13d 100644
--- a/docs/mllib-feature-extraction.md
+++ b/docs/mllib-feature-extraction.md
@@ -410,6 +410,7 @@ import org.apache.spark.SparkContext._
 import org.apache.spark.mllib.linalg.Vectors
 import org.apache.spark.mllib.regression.LabeledPoint
 import org.apache.spark.mllib.util.MLUtils
+import org.apache.spark.mllib.feature.ChiSqSelector
 
 // Load some data in libsvm format
 val data = MLUtils.loadLibSVMFile(sc, "data/mllib/sample_libsvm_data.txt")
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/feature/ChiSqSelector.scala b/mllib/src/main/scala/org/apache/spark/mllib/feature/ChiSqSelector.scala
index 9cc2d0ffca..5f8c1dea23 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/feature/ChiSqSelector.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/feature/ChiSqSelector.scala
@@ -108,7 +108,7 @@ class ChiSqSelectorModel (val selectedFeatures: Array[Int]) extends VectorTransf
  *                       (ordered by statistic value descending)
  */
 @Experimental
-class ChiSqSelector (val numTopFeatures: Int) {
+class ChiSqSelector (val numTopFeatures: Int) extends Serializable {
 
   /**
    * Returns a ChiSquared feature selector.