diff --git a/core/src/main/scala/org/apache/spark/ui/storage/BlockManagerUI.scala b/core/src/main/scala/org/apache/spark/ui/storage/BlockManagerUI.scala
index 4d8b01dbe6e1b..a7b24ff695214 100644
--- a/core/src/main/scala/org/apache/spark/ui/storage/BlockManagerUI.scala
+++ b/core/src/main/scala/org/apache/spark/ui/storage/BlockManagerUI.scala
@@ -84,7 +84,7 @@ private[ui] class BlockManagerListener(storageStatusListener: StorageStatusListe
 
   override def onStageSubmitted(stageSubmitted: SparkListenerStageSubmitted) = synchronized {
     val rddInfo = stageSubmitted.stageInfo.rddInfo
-    _rddInfoMap(rddInfo.id) = rddInfo
+    _rddInfoMap.getOrElseUpdate(rddInfo.id, rddInfo)
   }
 
   override def onStageCompleted(stageCompleted: SparkListenerStageCompleted) = synchronized {