diff --git a/mllib/src/main/scala/org/apache/spark/mllib/fpm/PrefixSpan.scala b/mllib/src/main/scala/org/apache/spark/mllib/fpm/PrefixSpan.scala
index 69e4b76b2d8c..25605d1d3591 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/fpm/PrefixSpan.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/fpm/PrefixSpan.scala
@@ -217,6 +217,7 @@ object PrefixSpan extends Logging {
       data: RDD[Array[Array[Item]]],
       minCount: Long): Array[Item] = {
 
+    data.persist()
     data.flatMap { itemsets =>
       val uniqItems = mutable.Set.empty[Item]
       itemsets.foreach(set => uniqItems ++= set)