diff --git a/bin/moonc b/bin/moonc
index 44f412d..313a650 100644
--- a/bin/moonc
+++ b/bin/moonc
@@ -26,7 +26,7 @@ parser:flag("-",
 local read_stdin = arg[1] == "-" -- luacheck: ignore 113
 
 if not read_stdin then
-  parser:argument("file/directory"):args("+")
+  parser:argument("file/directory"):args("*")
 else
   if arg[2] ~= nil then
     io.stderr:write("- must be the only argument\n")
@@ -42,6 +42,11 @@ if opts.version then
   os.exit()
 end
 
+if not read_stdin and #opts["file/directory"] == 0 then
+  io.stderr:write(parser:get_help())
+  os.exit()
+end
+
 function log_msg(...)
   if not opts.p then
     io.stderr:write(table.concat({...}, " ") .. "\n")