fix usage printing

diff --git a/libs/json/parser_tests/test_parser.ml b/libs/json/parser_tests/test_parser.ml
index 1f620c5100560056827bec662816989e712f1597..8ab861e5cb0ad365c6f6d199419665de6e4ea15f 100644 (file)
--- a/libs/json/parser_tests/test_parser.ml
+++ b/libs/json/parser_tests/test_parser.ml
@@ -22,7 +22,7 @@ let parse_args () =
        Arg.parse (Arg.align options) (fun f -> file := Some f) usage;
        match !file with
        | Some f -> f
-       | None -> Printf.eprintf "%s\n" usage; exit 1
+       | None -> Arg.usage (Arg.align options) usage; exit 1
 
 let read_whole_file ic =
        let buf = Buffer.create 512 in