diff --git a/launcher/src/main/java/org/apache/spark/launcher/SparkSubmitCommandBuilder.java b/launcher/src/main/java/org/apache/spark/launcher/SparkSubmitCommandBuilder.java
index 629200bcc3aea..698f2b4ec25e3 100644
--- a/launcher/src/main/java/org/apache/spark/launcher/SparkSubmitCommandBuilder.java
+++ b/launcher/src/main/java/org/apache/spark/launcher/SparkSubmitCommandBuilder.java
@@ -308,7 +308,8 @@ private boolean isClientMode(Properties userProps) {
    * Return whether the given main class represents a thrift server.
    */
   private boolean isThriftServer(String mainClass) {
-    return mainClass.equals("org.apache.spark.sql.hive.thriftserver.HiveThriftServer2");
+    return (mainClass != null &&
+        mainClass.equals("org.apache.spark.sql.hive.thriftserver.HiveThriftServer2"));
   }