diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/util/HostsFileWriter.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/util/HostsFileWriter.java
index e171e2bbdc..9dd788d166 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/util/HostsFileWriter.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/util/HostsFileWriter.java
@@ -106,6 +106,10 @@ public void initOutOfServiceHosts(List<String> decommissionHostNameAndPorts,
         for (String hostNameAndPort : decommissionHostNameAndPorts) {
           DatanodeAdminProperties dn = new DatanodeAdminProperties();
           String[] hostAndPort = hostNameAndPort.split(":");
+          if (hostAndPort.length != 2) {
+            throw new IllegalArgumentException("The decommision host name and port format is "
+                + "invalid. The format should be in <host>:<port>, not " + hostNameAndPort);
+          }
           dn.setHostName(hostAndPort[0]);
           dn.setPort(Integer.parseInt(hostAndPort[1]));
           dn.setAdminState(AdminStates.DECOMMISSIONED);