diff --git a/opam b/opam
index 7e70816f..5250bcf7 100644
--- a/opam
+++ b/opam
@@ -30,7 +30,7 @@ depends: [
   "yojson" {>= "1.6.0"}
   "resource-pooling" {>= "1.0" & < "2.0"}
   "cohttp-lwt-unix"
-  "js_of_ocaml" {>= "5.5.0"}
+  "js_of_ocaml" {>= "6.0.0"}
   "re" {>= "1.7.2"}
 ]
 depexts: [
diff --git a/src/os_handlers.eliom b/src/os_handlers.eliom
index 8a30a238..abab3aeb 100644
--- a/src/os_handlers.eliom
+++ b/src/os_handlers.eliom
@@ -23,11 +23,7 @@
 open%client Eliom_content.Html.F
 open%client Js_of_ocaml
 
-let%client storage () =
-  Js.Optdef.case
-    Dom_html.window##.localStorage
-    (fun () -> failwith "Browser storage not supported")
-    (fun v -> v)
+let%client storage () = Dom_html.window##.localStorage
 
 (* Set personal data *)
 let%server set_personal_data_handler myid ()
diff --git a/src/os_tips.eliom b/src/os_tips.eliom
index d8c7fc3d..ee430d5d 100644
--- a/src/os_tips.eliom
+++ b/src/os_tips.eliom
@@ -218,7 +218,7 @@ let%client display_bubble ?(a = []) ?arrow ?top ?left ?right ?bottom ?height
   let%lwt () = Lwt_js.sleep delay in
   let box = To_dom.of_element box in
   Dom.appendChild parent_node box;
-  box##.style##.opacity := Js.def (Js.string "0");
+  box##.style##.opacity := Js.string "0";
   Eliom_lib.Option.iter
     (fun v -> box##.style##.top := Js.string (Printf.sprintf "%ipx" v))
     top;
@@ -265,7 +265,7 @@ let%client display_bubble ?(a = []) ?arrow ?top ?left ?right ?bottom ?height
            bec##.style##.borderLeft := Js.string "none")
     arrow;
   let%lwt () = Lwt_js_events.request_animation_frame () in
-  box##.style##.opacity := Js.def (Js.string "1");
+  box##.style##.opacity := Js.string "1";
   Lwt.return_unit
 
 (* Function to be called on server to display a tip *)