diff --git a/tools/lsmcli/cmdline.py b/tools/lsmcli/cmdline.py
index ae249b8..6698c53 100644
--- a/tools/lsmcli/cmdline.py
+++ b/tools/lsmcli/cmdline.py
@@ -1228,6 +1228,7 @@ def cli(self):
         _add_common_options(parser, is_child=False)
 
         subparsers = parser.add_subparsers(metavar="command")
+        subparsers.required = True
 
         # Walk the command list and add all of them to the parser
         for cmd in cmds: