diff --git a/erlang/apps/od/src/od.erl b/erlang/apps/od/src/od.erl
index 0ff5fdf..d7fca55 100644
--- a/erlang/apps/od/src/od.erl
+++ b/erlang/apps/od/src/od.erl
@@ -1,7 +1,7 @@
 %%% -*- erlang-indent-level: 2 -*-
 %%%
 %%% 'od' clone for files with 9-bit bytes
-%%% Copyright (C) 2013-2019  Mikael Pettersson
+%%% Copyright (C) 2013-2020  Mikael Pettersson
 %%%
 %%% This file is part of pdp10-tools.
 %%%
@@ -41,6 +41,7 @@
 main(Argv) ->
   escript_runtime:start(fun main_/1, Argv).
 
+-spec main_([string()]) -> no_return().
 main_(Argv) ->
   case getopt:parse(Argv, "VbcdDiloOsxXA:j:N:t:w::",
                     [ {"version", no, $V}