diff --git a/lcpng_if_cli.c b/lcpng_if_cli.c
index ff022af..d237092 100644
--- a/lcpng_if_cli.c
+++ b/lcpng_if_cli.c
@@ -179,6 +179,7 @@ static clib_error_t *lcp_default_netns_command_fn(vlib_main_t *vm,
   unformat_input_t _line_input, *line_input = &_line_input;
   u8 *ns;
   int r;
+  clib_error_t *error = NULL;
 
   if (!unformat_user(input, unformat_line_input, line_input))
     return 0;
@@ -190,10 +191,15 @@ static clib_error_t *lcp_default_netns_command_fn(vlib_main_t *vm,
       ;
     else if (unformat(line_input, "clear netns"))
       ;
+    else
+      {
+	vec_free (ns);
+	error = clib_error_return (0, "unknown input `%U'",
+				   format_unformat_error, line_input);
+	goto done;
+      }
   }
 
-  unformat_free(line_input);
-
   vlib_cli_output(vm, "lcp set default netns %v\n", ns);
 
   r = lcp_set_default_ns(ns);
@@ -201,7 +207,10 @@ static clib_error_t *lcp_default_netns_command_fn(vlib_main_t *vm,
   if (r)
     return clib_error_return(0, "linux-cp set default netns failed (%d)", r);
 
-  return 0;
+done:
+  unformat_free (line_input);
+
+  return error;
 }
 
 VLIB_CLI_COMMAND(lcp_default_netns_command, static) = {