diff --git a/core/src/main/scala/org/apache/spark/SecurityManager.scala b/core/src/main/scala/org/apache/spark/SecurityManager.scala
index 12b15fe0815bea7afb16a45142836d70f7ac7b13..3832a780ec4bc1ef18c4ff47bfcbc24962dfa51b 100644
--- a/core/src/main/scala/org/apache/spark/SecurityManager.scala
+++ b/core/src/main/scala/org/apache/spark/SecurityManager.scala
@@ -162,7 +162,7 @@ private[spark] class SecurityManager(sparkConf: SparkConf) extends Logging {
 
   // always add the current user and SPARK_USER to the viewAcls
   private val defaultAclUsers = Set[String](System.getProperty("user.name", ""),
-    Option(System.getenv("SPARK_USER")).getOrElse(""))
+    Option(System.getenv("SPARK_USER")).getOrElse("")).filter(!_.isEmpty)
 
   setViewAcls(defaultAclUsers, sparkConf.get("spark.ui.view.acls", ""))
   setModifyAcls(defaultAclUsers, sparkConf.get("spark.modify.acls", ""))