diff --git a/hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/tools/federation/RouterAdmin.java b/hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/tools/federation/RouterAdmin.java
index 91e1669ed9..f88d0a60eb 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/tools/federation/RouterAdmin.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/tools/federation/RouterAdmin.java
@@ -218,6 +218,10 @@ public int run(String[] argv) throws Exception {
               "Successfully clear quota for mount point " + argv[i]);
         }
       } else if ("-safemode".equals(cmd)) {
+        if (argv.length > 2) {
+          throw new IllegalArgumentException(
+              "Too many arguments, Max=1 argument allowed only");
+        }
         manageSafeMode(argv[i]);
       } else if ("-nameservice".equals(cmd)) {
         String subcmd = argv[i];
@@ -712,6 +716,8 @@ private void manageSafeMode(String cmd) throws IOException {
     } else if (cmd.equals("get")) {
       boolean result = getSafeMode();
       System.out.println("Safe Mode: " + result);
+    } else {
+      throw new IllegalArgumentException("Invalid argument: " + cmd);
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestRouterAdminCLI.java b/hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestRouterAdminCLI.java
index 2da5fb9540..2682e9a2d8 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestRouterAdminCLI.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestRouterAdminCLI.java
@@ -519,6 +519,7 @@ public void testManageSafeMode() throws Exception {
     assertTrue(routerContext.getRouter().getSafemodeService().isInSafeMode());
 
     System.setOut(new PrintStream(out));
+    System.setErr(new PrintStream(err));
     assertEquals(0, ToolRunner.run(admin,
         new String[] {"-safemode", "get"}));
     assertTrue(out.toString().contains("true"));
@@ -534,6 +535,19 @@ public void testManageSafeMode() throws Exception {
     assertEquals(0, ToolRunner.run(admin,
         new String[] {"-safemode", "get"}));
     assertTrue(out.toString().contains("false"));
+
+    out.reset();
+    assertEquals(-1, ToolRunner.run(admin,
+        new String[] {"-safemode", "get", "-random", "check" }));
+    assertTrue(err.toString(), err.toString()
+        .contains("safemode: Too many arguments, Max=1 argument allowed only"));
+    err.reset();
+
+    assertEquals(-1,
+        ToolRunner.run(admin, new String[] {"-safemode", "check" }));
+    assertTrue(err.toString(),
+        err.toString().contains("safemode: Invalid argument: check"));
+    err.reset();
   }
 
   @Test