diff --git a/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala b/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala
index 17cdba4f1305..ab020aaf6fa4 100644
--- a/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala
+++ b/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala
@@ -47,7 +47,7 @@ private[spark] abstract class StreamFileInputFormat[T]
   def setMinPartitions(sc: SparkContext, context: JobContext, minPartitions: Int) {
     val defaultMaxSplitBytes = sc.getConf.get(config.FILES_MAX_PARTITION_BYTES)
     val openCostInBytes = sc.getConf.get(config.FILES_OPEN_COST_IN_BYTES)
-    val defaultParallelism = sc.defaultParallelism
+    val defaultParallelism = Math.max(sc.defaultParallelism, minPartitions)
     val files = listStatus(context).asScala
     val totalBytes = files.filterNot(_.isDirectory).map(_.getLen + openCostInBytes).sum
     val bytesPerCore = totalBytes / defaultParallelism