diff --git a/src/tools/why3extract.ml b/src/tools/why3extract.ml
index fe91df7aca7c6cc2a09d310b3a201d8ca69a29a7..cc4b529db6b2f2957b7b77a376364cd5c23835dd 100644
--- a/src/tools/why3extract.ml
+++ b/src/tools/why3extract.ml
@@ -165,7 +165,7 @@ let print_mdecls ?fname m mdecls deps =
     if !opt_interface then begin
       match printer.Pdriver.interf_gen, printer.Pdriver.interf_printer with
       | None, _ | _, None ->
-         eprintf "Driver does not support interface extraction";
+         eprintf "Driver does not support interface extraction.@.";
          exit 1
       | Some ig, Some ipr ->
          let iout, old = get_cout_old ig m ?fname in