diff --git a/core/src/main/scala/spark/ui/exec/ExecutorsUI.scala b/core/src/main/scala/spark/ui/exec/ExecutorsUI.scala
index 6ec48f70a456a79e79e982dcb20b21510b222f35..43e0c20b19a9e0d95a302ae1225588f37918af39 100644
--- a/core/src/main/scala/spark/ui/exec/ExecutorsUI.scala
+++ b/core/src/main/scala/spark/ui/exec/ExecutorsUI.scala
@@ -38,10 +38,9 @@ private[spark] class ExecutorsUI(val sc: SparkContext) {
   def render(request: HttpServletRequest): Seq[Node] = {
     val storageStatusList = sc.getExecutorStorageStatus
 
-    val maxMem = storageStatusList.map(_.maxMem).reduce(_+_)
-    val memUsed = storageStatusList.map(_.memUsed()).reduce(_+_)
-    val diskSpaceUsed = storageStatusList.flatMap(_.blocks.values.map(_.diskSize))
-      .reduceOption(_+_).getOrElse(0L)
+    val maxMem = storageStatusList.map(_.maxMem).fold(0L)(_+_)
+    val memUsed = storageStatusList.map(_.memUsed()).fold(0L)(_+_)
+    val diskSpaceUsed = storageStatusList.flatMap(_.blocks.values.map(_.diskSize)).fold(0L)(_+_)
 
     val execHead = Seq("Executor ID", "Address", "RDD blocks", "Memory used", "Disk used",
       "Active tasks", "Failed tasks", "Complete tasks", "Total tasks")
@@ -93,10 +92,9 @@ private[spark] class ExecutorsUI(val sc: SparkContext) {
     val memUsed = sc.getExecutorStorageStatus(a).memUsed().toString
     val maxMem = sc.getExecutorStorageStatus(a).maxMem.toString
     val diskUsed = sc.getExecutorStorageStatus(a).diskUsed().toString
-    val activeTasks = listener.executorToTasksActive.get(a.toString).map(l => l.size)
-      .getOrElse(0).toString
-    val failedTasks = listener.executorToTasksFailed.getOrElse(a.toString, 0).toString
-    val completedTasks = listener.executorToTasksComplete.getOrElse(a.toString, 0).toString
+    val activeTasks = listener.executorToTasksActive.get(a.toString).map(l => l.size).getOrElse(0)
+    val failedTasks = listener.executorToTasksFailed.getOrElse(a.toString, 0)
+    val completedTasks = listener.executorToTasksComplete.getOrElse(a.toString, 0)
     val totalTasks = activeTasks + failedTasks + completedTasks
 
     Seq(
@@ -106,10 +104,10 @@ private[spark] class ExecutorsUI(val sc: SparkContext) {
       memUsed,
       maxMem,
       diskUsed,
-      activeTasks,
-      failedTasks,
-      completedTasks,
-      totalTasks
+      activeTasks.toString,
+      failedTasks.toString,
+      completedTasks.toString,
+      totalTasks.toString
     )
   }