diff --git a/lib/file.ml b/lib/file.ml
index 1754df3b4a..b79cf07085 100644
--- a/lib/file.ml
+++ b/lib/file.ml
@@ -140,44 +140,7 @@ let read_with_filereader (fileReader : fileReader t constr) kind file =
     | `DataURL -> reader##readAsDataURL(file));
   res
 
-(* Old firefox specific part: available in firefox 3.0, deprecated in 3.6.
-   Those are nonstandard extensions. *)
-class type old_firefox_file =
-object
-  method getAsBinary : js_string t meth
-  method getAsBinary_presence : unit optdef readonly_prop
-  method getAsDataURL : js_string t meth
-  method getAsDataURL_presence : unit optdef readonly_prop
-  method getAsText_presence : unit optdef readonly_prop
-  method getAsText : js_string t -> js_string t meth
-end
-
-let old_firefox_reader kind file =
-  let file = (Js.Unsafe.coerce file:old_firefox_file t) in
-  let fail () = failwith "browser can't read file: unimplemented" in
-  match kind with
-    | `BinaryString ->
-      if Js.Optdef.test ( file##getAsBinary_presence )
-      then file##getAsBinary()
-      else fail ()
-    | `Text ->
-      if Js.Optdef.test ( file##getAsText_presence )
-      then file##getAsText(Js.string "utf8")
-      else fail ()
-    | `Text_withEncoding e ->
-      if Js.Optdef.test ( file##getAsText_presence )
-      then file##getAsText(e)
-      else fail ()
-    | `DataURL ->
-      if Js.Optdef.test ( file##getAsDataURL_presence )
-      then file##getAsDataURL()
-      else fail ()
-(* end of old firefox specific part *)
-
-let reader kind file =
-  match Js.Optdef.to_option (Js.def fileReader) with
-    | None -> Lwt.return (old_firefox_reader kind file)
-    | Some fileReader -> read_with_filereader fileReader kind file
+let reader kind file = read_with_filereader fileReader kind file
 
 let readAsBinaryString file =
   reader `BinaryString file
diff --git a/lib/xmlHttpRequest.ml b/lib/xmlHttpRequest.ml
index f62484b4bc..19700afbba 100644
--- a/lib/xmlHttpRequest.ml
+++ b/lib/xmlHttpRequest.ml
@@ -124,10 +124,6 @@ let encode_url l =
 	 | name,`File s -> ((Url.urlencode name) ^ "=" ^ (Url.urlencode (to_string (s##name))))
 ) l)
 
-let partition_string_file l = List.partition (function
-  | _,`String _ -> true
-  | _,`File _ -> false ) l
-
 (* Higher level interface: *)
 
 (** type of the http headers *)
@@ -186,20 +182,15 @@ let perform_raw_url
 	Some form_arg
   in
 
-  let method_, content_type, post_encode =
+  let method_, content_type =
     match form_arg, content_type with
-      | None, ct -> "GET", ct, `Urlencode
+      | None, ct -> "GET", ct
       | Some form_args, None ->
 	(match form_args with
-	  | `Fields l ->
-	    let strings,files = partition_string_file !l in
-	    (match files with
-	      | [] -> "POST", (Some "application/x-www-form-urlencoded"), `Urlencode
-	      | _ ->
-		let boundary = generateBoundary () in
-		"POST", (Some ("multipart/form-data; boundary="^boundary)), `Form_data (boundary))
-	  | `FormData f -> "POST", None, `Urlencode)
-      | Some _, ct -> "POST", ct, `Urlencode
+	  | `Fields strings ->
+               "POST", Some "application/x-www-form-urlencoded"
+	  | `FormData f -> "POST", None)
+      | Some _, ct -> "POST", ct
   in
   let url, url_get = extract_get_param url in
   let url = match url_get@get_args with
@@ -286,19 +277,7 @@ let perform_raw_url
   (match form_arg with
      | None -> req##send (Js.null)
      | Some (`Fields l) ->
-       ignore (
-	 match post_encode with
-	   | `Urlencode -> req##send(Js.some (string (encode_url !l)));return ()
-	   | `Form_data boundary ->
-	     (encode_multipart boundary !l >|=
-		 (fun data ->
-		   let data = Js.some (data##join(Js.string "")) in
-		   (* Firefox specific interface:
-		      Chrome can use FormData: don't need this *)
-		   let req = (Js.Unsafe.coerce req:xmlHttpRequest_binary t) in
-		   if Optdef.test req##sendAsBinary_presence
-		   then req##sendAsBinary(data)
-		   else req##send(data))))
+         ignore (req##send(Js.some (string (encode_url !l)));return ())
      | Some (`FormData f) -> req##send_formData(f));
 
   Lwt.on_cancel res (fun () -> req##abort ()) ;