diff --git a/test/lwt/echo_server.ml b/test/lwt/echo_server.ml
index 8b1c8af8..a1ba88aa 100644
--- a/test/lwt/echo_server.ml
+++ b/test/lwt/echo_server.ml
@@ -62,4 +62,5 @@ let () =
   Arg.parse opts ignore "echo server";
 
   let@ runner = M.Ws_pool.with_ ~name:"tpool" ~num_threads:!j () in
+  Lwt_engine.set @@ new Lwt_engine.libev ();
   Lwt_main.run @@ main ~runner ~port:!port ()