diff --git a/.gitignore b/.gitignore
index 3fa15bf..1a88130 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,3 +14,4 @@ setup.log
 _build
 *.native
 .*.swp
+_tests/*
diff --git a/.merlin b/.merlin
new file mode 100644
index 0000000..bf3fb89
--- /dev/null
+++ b/.merlin
@@ -0,0 +1,5 @@
+PKG lwt alcotest cstruct tuntap io-page
+S lib/
+S lib_test/
+B _build/lib/
+B _build/
diff --git a/.travis.yml b/.travis.yml
index d0ae7e4..3f0807a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,5 +2,8 @@ language: c
 install: wget https://raw.githubusercontent.com/ocaml/ocaml-travisci-skeleton/master/.travis-opam.sh
 script: bash -ex .travis-opam.sh
 env:
-  - OCAML_VERSION=4.01
+  global:
+  - PACKAGE=mirage-net-unix
+  matrix:
   - OCAML_VERSION=4.02
+  - OCAML_VERSION=4.03
diff --git a/Makefile b/Makefile
index 8c9c0a7..6775f2d 100644
--- a/Makefile
+++ b/Makefile
@@ -12,7 +12,7 @@ setup.bin: setup.ml
 	@rm -f setup.cmx setup.cmi setup.o setup.cmo
 
 setup.data: setup.bin
-	@./setup.bin -configure --enable-tests
+	@./setup.bin -configure $(CONFIGUREFLAGS)
 
 build: setup.data setup.bin
 	@./setup.bin -build -j $(J)
@@ -26,7 +26,9 @@ install: setup.bin
 uninstall:
 	@ocamlfind remove $(NAME) || true
 
-test: setup.bin build
+test: setup.bin
+	@./setup.bin -configure --enable-tests
+	@./setup.bin -build -j $(J)
 	@./setup.bin -test
 
 reinstall: setup.bin
diff --git a/_oasis b/_oasis
index 027625e..78d96be 100644
--- a/_oasis
+++ b/_oasis
@@ -21,7 +21,7 @@ Executable test
   MainIs:             test.ml
   Custom:             true
   Install:            false
-  BuildDepends:       lwt, lwt.unix, mirage-net-unix, cstruct, oUnit, io-page.unix, io-page
+  BuildDepends:       lwt, lwt.unix, mirage-net-unix, cstruct, alcotest, io-page.unix, io-page
 
 Test test
   Run$:             flag(tests)
diff --git a/_tags b/_tags
index 8b6b420..9c84f53 100644
--- a/_tags
+++ b/_tags
@@ -1,5 +1,5 @@
 # OASIS_START
-# DO NOT EDIT (digest: 7adba8fcc5769d2c5df14f6fc4a2c06a)
+# DO NOT EDIT (digest: e2a972a46ecf908b3818d7dca4061cda)
 # Ignore VCS directories, you can use the same kind of rule outside
 # OASIS_START/STOP if you want to exclude directories that contains
 # useless stuff for the build process
@@ -23,6 +23,7 @@ true: annot, bin_annot
 <lib/*.ml{,i,y}>: pkg_mirage-types
 <lib/*.ml{,i,y}>: pkg_tuntap
 # Executable test
+<lib_test/test.{native,byte}>: pkg_alcotest
 <lib_test/test.{native,byte}>: pkg_cstruct
 <lib_test/test.{native,byte}>: pkg_cstruct.lwt
 <lib_test/test.{native,byte}>: pkg_io-page
@@ -30,9 +31,9 @@ true: annot, bin_annot
 <lib_test/test.{native,byte}>: pkg_lwt
 <lib_test/test.{native,byte}>: pkg_lwt.unix
 <lib_test/test.{native,byte}>: pkg_mirage-types
-<lib_test/test.{native,byte}>: pkg_oUnit
 <lib_test/test.{native,byte}>: pkg_tuntap
 <lib_test/test.{native,byte}>: use_mirage-net-unix
+<lib_test/*.ml{,i,y}>: pkg_alcotest
 <lib_test/*.ml{,i,y}>: pkg_cstruct
 <lib_test/*.ml{,i,y}>: pkg_cstruct.lwt
 <lib_test/*.ml{,i,y}>: pkg_io-page
@@ -40,7 +41,6 @@ true: annot, bin_annot
 <lib_test/*.ml{,i,y}>: pkg_lwt
 <lib_test/*.ml{,i,y}>: pkg_lwt.unix
 <lib_test/*.ml{,i,y}>: pkg_mirage-types
-<lib_test/*.ml{,i,y}>: pkg_oUnit
 <lib_test/*.ml{,i,y}>: pkg_tuntap
 <lib_test/*.ml{,i,y}>: use_mirage-net-unix
 <lib_test/test.{native,byte}>: custom
diff --git a/lib/netif.ml b/lib/netif.ml
index d128e8a..ef5134c 100644
--- a/lib/netif.ml
+++ b/lib/netif.ml
@@ -64,7 +64,6 @@ let err_permission_denied devname =
 let err_partial_write len' page =
   fail "tap: partial write (%d, expected %d)" len' page.Cstruct.len
 
-
 let connect devname =
   try
     Random.self_init ();
@@ -87,7 +86,9 @@ let connect devname =
 
 let disconnect t =
   log "disconnect %s" t.id;
-  Tuntap.closetun t.id;
+  t.active <- false;
+  Lwt_unix.close t.dev >>= fun () ->
+  Tuntap.closetap t.id;
   Lwt.return_unit
 
 type macaddr = Macaddr.t
@@ -152,30 +153,21 @@ let rec listen t fn =
     listen t fn
   | false -> Lwt.return_unit
 
-(* Transmit a packet from an Io_page *)
-let write t page =
+(* Transmit a packet from a Cstruct.t *)
+let write t buffer =
   let open Cstruct in
   (* Unfortunately we peek inside the cstruct type here: *)
-  Lwt_bytes.write t.dev page.buffer page.off page.len >>= fun len' ->
+  Lwt_bytes.write t.dev buffer.buffer buffer.off buffer.len >>= fun len' ->
   t.stats.tx_pkts <- Int32.succ t.stats.tx_pkts;
-  t.stats.tx_bytes <- Int64.add t.stats.tx_bytes (Int64.of_int page.len);
-  if len' <> page.len then err_partial_write len' page
+  t.stats.tx_bytes <- Int64.add t.stats.tx_bytes (Int64.of_int buffer.len);
+  if len' <> buffer.len then err_partial_write len' buffer
   else Lwt.return_unit
 
-(* TODO use writev: but do a copy for now *)
 let writev t = function
   | []     -> Lwt.return_unit
   | [page] -> write t page
   | pages  ->
-    let page = Io_page.(to_cstruct (get 1)) in
-    let off = ref 0 in
-    List.iter (fun p ->
-        let len = Cstruct.len p in
-        Cstruct.blit p 0 page !off len;
-        off := !off + len;
-      ) pages;
-    let v = Cstruct.sub page 0 !off in
-    write t v
+    write t @@ Cstruct.concat pages
 
 let mac t = t.mac
 
diff --git a/lib_test/test.ml b/lib_test/test.ml
index 8051e0d..b1b591b 100644
--- a/lib_test/test.ml
+++ b/lib_test/test.ml
@@ -15,9 +15,11 @@
  *)
 
 open Lwt
-open OUnit
 open Printf
 
+let run test =
+  Lwt_main.run (test ())
+
 let err_connect e =
   let buf = Buffer.create 10 in
   let fmt = Format.formatter_of_buffer buf in
@@ -25,26 +27,35 @@ let err_connect e =
   failwith (Buffer.contents buf)
 
 let test_open () =
-  let thread =
-    Netif.connect "tap0" >>= function
-    | `Error e -> err_connect e
-    | `Ok t    ->
-      printf "connected\n%!";
-      Netif.listen t (fun buf ->
-          printf "got packet of len %d\n%!" (Cstruct.len buf);
-          Lwt.return_unit
-        )
-  in
-  Lwt_main.run thread
+  Netif.connect "tap0" >>= function
+  | `Error e -> err_connect e
+  | `Ok _t    ->
+    printf "connected\n%!";
+    Lwt.return_unit
+
+let test_close () =
+  Netif.connect "tap1" >>= function
+  | `Error e -> err_connect e
+  | `Ok t    ->
+    printf "connected\n%!";
+    Netif.disconnect t >>= function () ->
+    printf "disconnected\n%!";
+    Lwt.return_unit
+
+let test_write () =
+  Netif.connect "tap2" >>= function
+  | `Error e -> err_connect e
+  | `Ok t    ->
+    let data = Cstruct.create 4096 in
+    Netif.writev t [ data ] >>= fun () ->
+    Netif.writev t [ data ; (Cstruct.create 14) ] >>= fun () ->
+    Lwt.return_unit
+
+let suite : Alcotest.test_case list = [
+  "connect", `Quick, (fun () -> run test_open) ;
+  "disconnect", `Quick, (fun () -> run test_close);
+  "write", `Quick, (fun () -> run test_write);
+]
 
 let _ =
-  let verbose = ref false in
-  Arg.parse [
-    "-verbose", Arg.Unit (fun _ -> verbose := true), "Run in verbose mode";
-  ] (fun x -> Printf.fprintf stderr "Ignoring argument: %s" x)
-    "Test unix net driver";
-
-  let suite = "net" >::: [
-      "test open" >:: test_open;
-    ] in
-  run_test_tt ~verbose:!verbose suite
+  Alcotest.run "mirage-net-unix" [ "tests", suite ]
diff --git a/myocamlbuild.ml b/myocamlbuild.ml
index 7be4842..b454267 100644
--- a/myocamlbuild.ml
+++ b/myocamlbuild.ml
@@ -1,5 +1,5 @@
 (* OASIS_START *)
-(* DO NOT EDIT (digest: a0716e785352706021093042bece5760) *)
+(* DO NOT EDIT (digest: fcd72908a1049f5e9fbc426b31d2040e) *)
 module OASISGettext = struct
 (* # 22 "src/oasis/OASISGettext.ml" *)
 
@@ -29,6 +29,166 @@ module OASISGettext = struct
 
 end
 
+module OASISString = struct
+(* # 22 "src/oasis/OASISString.ml" *)
+
+
+  (** Various string utilities.
+
+      Mostly inspired by extlib and batteries ExtString and BatString libraries.
+
+      @author Sylvain Le Gall
+    *)
+
+
+  let nsplitf str f =
+    if str = "" then
+      []
+    else
+      let buf = Buffer.create 13 in
+      let lst = ref [] in
+      let push () =
+        lst := Buffer.contents buf :: !lst;
+        Buffer.clear buf
+      in
+      let str_len = String.length str in
+        for i = 0 to str_len - 1 do
+          if f str.[i] then
+            push ()
+          else
+            Buffer.add_char buf str.[i]
+        done;
+        push ();
+        List.rev !lst
+
+
+  (** [nsplit c s] Split the string [s] at char [c]. It doesn't include the
+      separator.
+    *)
+  let nsplit str c =
+    nsplitf str ((=) c)
+
+
+  let find ~what ?(offset=0) str =
+    let what_idx = ref 0 in
+    let str_idx = ref offset in
+      while !str_idx < String.length str &&
+            !what_idx < String.length what do
+        if str.[!str_idx] = what.[!what_idx] then
+          incr what_idx
+        else
+          what_idx := 0;
+        incr str_idx
+      done;
+      if !what_idx <> String.length what then
+        raise Not_found
+      else
+        !str_idx - !what_idx
+
+
+  let sub_start str len =
+    let str_len = String.length str in
+    if len >= str_len then
+      ""
+    else
+      String.sub str len (str_len - len)
+
+
+  let sub_end ?(offset=0) str len =
+    let str_len = String.length str in
+    if len >= str_len then
+      ""
+    else
+      String.sub str 0 (str_len - len)
+
+
+  let starts_with ~what ?(offset=0) str =
+    let what_idx = ref 0 in
+    let str_idx = ref offset in
+    let ok = ref true in
+      while !ok &&
+            !str_idx < String.length str &&
+            !what_idx < String.length what do
+        if str.[!str_idx] = what.[!what_idx] then
+          incr what_idx
+        else
+          ok := false;
+        incr str_idx
+      done;
+      if !what_idx = String.length what then
+        true
+      else
+        false
+
+
+  let strip_starts_with ~what str =
+    if starts_with ~what str then
+      sub_start str (String.length what)
+    else
+      raise Not_found
+
+
+  let ends_with ~what ?(offset=0) str =
+    let what_idx = ref ((String.length what) - 1) in
+    let str_idx = ref ((String.length str) - 1) in
+    let ok = ref true in
+      while !ok &&
+            offset <= !str_idx &&
+            0 <= !what_idx do
+        if str.[!str_idx] = what.[!what_idx] then
+          decr what_idx
+        else
+          ok := false;
+        decr str_idx
+      done;
+      if !what_idx = -1 then
+        true
+      else
+        false
+
+
+  let strip_ends_with ~what str =
+    if ends_with ~what str then
+      sub_end str (String.length what)
+    else
+      raise Not_found
+
+
+  let replace_chars f s =
+    let buf = Buffer.create (String.length s) in
+    String.iter (fun c -> Buffer.add_char buf (f c)) s;
+    Buffer.contents buf
+
+  let lowercase_ascii =
+    replace_chars
+      (fun c ->
+         if (c >= 'A' && c <= 'Z') then
+           Char.chr (Char.code c + 32)
+         else
+           c)
+
+  let uncapitalize_ascii s =
+    if s <> "" then
+      (lowercase_ascii (String.sub s 0 1)) ^ (String.sub s 1 ((String.length s) - 1))
+    else
+      s
+
+  let uppercase_ascii =
+    replace_chars
+      (fun c ->
+         if (c >= 'a' && c <= 'z') then
+           Char.chr (Char.code c - 32)
+         else
+           c)
+
+  let capitalize_ascii s =
+    if s <> "" then
+      (uppercase_ascii (String.sub s 0 1)) ^ (String.sub s 1 ((String.length s) - 1))
+    else
+      s
+
+end
+
 module OASISExpr = struct
 (* # 22 "src/oasis/OASISExpr.ml" *)
 
@@ -129,7 +289,7 @@ module OASISExpr = struct
 end
 
 
-# 132 "myocamlbuild.ml"
+# 292 "myocamlbuild.ml"
 module BaseEnvLight = struct
 (* # 22 "src/base/BaseEnvLight.ml" *)
 
@@ -234,7 +394,7 @@ module BaseEnvLight = struct
 end
 
 
-# 237 "myocamlbuild.ml"
+# 397 "myocamlbuild.ml"
 module MyOCamlbuildFindlib = struct
 (* # 22 "src/plugins/ocamlbuild/MyOCamlbuildFindlib.ml" *)
 
@@ -516,7 +676,7 @@ module MyOCamlbuildBase = struct
                  | nm, [], intf_modules ->
                      ocaml_lib nm;
                      let cmis =
-                       List.map (fun m -> (String.uncapitalize m) ^ ".cmi")
+                       List.map (fun m -> (OASISString.uncapitalize_ascii m) ^ ".cmi")
                                 intf_modules in
                      dep ["ocaml"; "link"; "library"; "file:"^nm^".cma"] cmis
                  | nm, dir :: tl, intf_modules ->
@@ -529,7 +689,7 @@ module MyOCamlbuildBase = struct
                             ["compile"; "infer_interface"; "doc"])
                        tl;
                      let cmis =
-                       List.map (fun m -> dir^"/"^(String.uncapitalize m)^".cmi")
+                       List.map (fun m -> dir^"/"^(OASISString.uncapitalize_ascii m)^".cmi")
                                 intf_modules in
                      dep ["ocaml"; "link"; "library"; "file:"^dir^"/"^nm^".cma"]
                          cmis)
@@ -603,7 +763,7 @@ module MyOCamlbuildBase = struct
 end
 
 
-# 606 "myocamlbuild.ml"
+# 766 "myocamlbuild.ml"
 open Ocamlbuild_plugin;;
 let package_default =
   {
@@ -618,7 +778,7 @@ let conf = {MyOCamlbuildFindlib.no_automatic_syntax = false}
 
 let dispatch_default = MyOCamlbuildBase.dispatch_default conf package_default;;
 
-# 622 "myocamlbuild.ml"
+# 782 "myocamlbuild.ml"
 (* OASIS_STOP *)
 Ocamlbuild_plugin.dispatch dispatch_default;;
 (* Ocamlbuild_pack.Flags.mark_tag_used "tests";; *)
diff --git a/opam b/opam
index 776f903..6e4dc45 100644
--- a/opam
+++ b/opam
@@ -15,12 +15,12 @@ build:   [make]
 install: [make "install"]
 remove:  ["ocamlfind" "remove" "mirage-net-unix"]
 depends: [
-  "cstruct" {>= "1.0.1"}
+  "cstruct" {>= "1.7.1"}
   "ocamlfind"
   "lwt" {>= "2.4.3"}
   "mirage-types" {>= "2.3.0"}
   "io-page" {>= "1.0.1"}
   "tuntap" {>= "1.3.0"}
-  "ounit" {build}
+  "alcotest" {test}
 ]
-available: [ ocaml-version >= "4.00.0"]
+available: [ ocaml-version >= "4.02.3"]
diff --git a/setup.ml b/setup.ml
index b9e7e52..daa531e 100644
--- a/setup.ml
+++ b/setup.ml
@@ -1,9 +1,9 @@
 (* setup.ml generated for the first time by OASIS v0.3.0 *)
 
 (* OASIS_START *)
-(* DO NOT EDIT (digest: c372dff9745db242f53b3ae816014804) *)
+(* DO NOT EDIT (digest: 67c2cb933d479b10d979d2ce355fda10) *)
 (*
-   Regenerated by OASIS v0.4.5
+   Regenerated by OASIS v0.4.6
    Visit http://oasis.forge.ocamlcore.org for more information and
    documentation about functions used in this file.
 *)
@@ -246,6 +246,33 @@ module OASISString = struct
     String.iter (fun c -> Buffer.add_char buf (f c)) s;
     Buffer.contents buf
 
+  let lowercase_ascii =
+    replace_chars
+      (fun c ->
+         if (c >= 'A' && c <= 'Z') then
+           Char.chr (Char.code c + 32)
+         else
+           c)
+
+  let uncapitalize_ascii s =
+    if s <> "" then
+      (lowercase_ascii (String.sub s 0 1)) ^ (String.sub s 1 ((String.length s) - 1))
+    else
+      s
+
+  let uppercase_ascii =
+    replace_chars
+      (fun c ->
+         if (c >= 'a' && c <= 'z') then
+           Char.chr (Char.code c - 32)
+         else
+           c)
+
+  let capitalize_ascii s =
+    if s <> "" then
+      (uppercase_ascii (String.sub s 0 1)) ^ (String.sub s 1 ((String.length s) - 1))
+    else
+      s
 
 end
 
@@ -315,19 +342,15 @@ module OASISUtils = struct
 
 
   let compare_csl s1 s2 =
-    String.compare (String.lowercase s1) (String.lowercase s2)
+    String.compare (OASISString.lowercase_ascii s1) (OASISString.lowercase_ascii s2)
 
 
   module HashStringCsl =
     Hashtbl.Make
       (struct
          type t = string
-
-         let equal s1 s2 =
-             (String.lowercase s1) = (String.lowercase s2)
-
-         let hash s =
-           Hashtbl.hash (String.lowercase s)
+         let equal s1 s2 = (compare_csl s1 s2) = 0
+         let hash s = Hashtbl.hash (OASISString.lowercase_ascii s)
        end)
 
   module SetStringCsl =
@@ -365,7 +388,7 @@ module OASISUtils = struct
           else
             buf
         in
-          String.lowercase buf
+          OASISString.lowercase_ascii buf
       end
 
 
@@ -471,7 +494,7 @@ module PropList = struct
         order     = Queue.create ();
         name_norm =
           (if case_insensitive then
-             String.lowercase
+             OASISString.lowercase_ascii
            else
              fun s -> s);
       }
@@ -1822,13 +1845,13 @@ module OASISUnixPath = struct
   let capitalize_file f =
     let dir = dirname f in
     let base = basename f in
-    concat dir (String.capitalize base)
+    concat dir (OASISString.capitalize_ascii base)
 
 
   let uncapitalize_file f =
     let dir = dirname f in
     let base = basename f in
-    concat dir (String.uncapitalize base)
+    concat dir (OASISString.uncapitalize_ascii base)
 
 
 end
@@ -2890,7 +2913,7 @@ module OASISFileUtil = struct
 end
 
 
-# 2893 "setup.ml"
+# 2916 "setup.ml"
 module BaseEnvLight = struct
 (* # 22 "src/base/BaseEnvLight.ml" *)
 
@@ -2995,7 +3018,7 @@ module BaseEnvLight = struct
 end
 
 
-# 2998 "setup.ml"
+# 3021 "setup.ml"
 module BaseContext = struct
 (* # 22 "src/base/BaseContext.ml" *)
 
@@ -5406,7 +5429,7 @@ module BaseSetup = struct
 end
 
 
-# 5409 "setup.ml"
+# 5432 "setup.ml"
 module InternalConfigurePlugin = struct
 (* # 22 "src/plugins/internal/InternalConfigurePlugin.ml" *)
 
@@ -5845,8 +5868,8 @@ module InternalInstallPlugin = struct
     let make_fnames modul sufx =
       List.fold_right
         begin fun sufx accu ->
-          (String.capitalize modul ^ sufx) ::
-          (String.uncapitalize modul ^ sufx) ::
+          (OASISString.capitalize_ascii modul ^ sufx) ::
+          (OASISString.uncapitalize_ascii modul ^ sufx) ::
           accu
         end
         sufx
@@ -6270,7 +6293,7 @@ module InternalInstallPlugin = struct
 end
 
 
-# 6273 "setup.ml"
+# 6296 "setup.ml"
 module OCamlbuildCommon = struct
 (* # 22 "src/plugins/ocamlbuild/OCamlbuildCommon.ml" *)
 
@@ -6648,7 +6671,7 @@ module OCamlbuildDocPlugin = struct
 end
 
 
-# 6651 "setup.ml"
+# 6674 "setup.ml"
 module CustomPlugin = struct
 (* # 22 "src/plugins/custom/CustomPlugin.ml" *)
 
@@ -6796,7 +6819,7 @@ module CustomPlugin = struct
 end
 
 
-# 6799 "setup.ml"
+# 6822 "setup.ml"
 open OASISTypes;;
 
 let setup_t =
@@ -6969,7 +6992,7 @@ let setup_t =
                            FindlibPackage ("lwt.unix", None);
                            InternalLibrary "mirage-net-unix";
                            FindlibPackage ("cstruct", None);
-                           FindlibPackage ("oUnit", None);
+                           FindlibPackage ("alcotest", None);
                            FindlibPackage ("io-page.unix", None);
                            FindlibPackage ("io-page", None)
                         ];
@@ -7018,8 +7041,8 @@ let setup_t =
           plugin_data = []
        };
      oasis_fn = Some "_oasis";
-     oasis_version = "0.4.5";
-     oasis_digest = Some "\247\254\236\191S\n\152mpd9H\021\217]\195";
+     oasis_version = "0.4.6";
+     oasis_digest = Some "\237\027\014*\248\241\216Gj\0314M~\164 8";
      oasis_exec = None;
      oasis_setup_args = [];
      setup_update = false
@@ -7027,6 +7050,6 @@ let setup_t =
 
 let setup () = BaseSetup.setup setup_t;;
 
-# 7031 "setup.ml"
+# 7054 "setup.ml"
 (* OASIS_STOP *)
 let () = setup ();;