diff --git a/CHANGES b/CHANGES
index 21e8994..f12a916 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,2 +1,2 @@
-0.1 (2013-06-09):
+0.1 (2013-06-10):
 * first alpha release
diff --git a/TODO b/TODO
index 58c4e79..7b10000 100644
--- a/TODO
+++ b/TODO
@@ -1,2 +1 @@
-* Fix Lwt type unification bug (that renders it unusable)
 * Async backend ?
diff --git a/lib/smtp.ml b/lib/smtp.ml
index dfc9e22..babbeb0 100644
--- a/lib/smtp.ml
+++ b/lib/smtp.ml
@@ -95,8 +95,8 @@ module Make (IO : IO) = struct
 
   let finally f g =
     try
-      let ret = f () in g (); ret
-    with exn -> g (); IO.fail exn
+      f () >>= fun ret -> g () >>= fun () -> IO.return ret
+    with exn -> g () >>= fun () -> IO.fail exn
 
   let sendmail ?(host="") ?(port="smtp") ~name ~from ~to_ ~body () =
     connect ~host ~port ~name () >>= fun h ->
diff --git a/lwt/smtp_lwt.ml b/lwt/smtp_lwt.ml
index 41099cd..447830f 100644
--- a/lwt/smtp_lwt.ml
+++ b/lwt/smtp_lwt.ml
@@ -1,4 +1,4 @@
-module IO : Smtp.IO = struct
+module IO = struct
   type 'a t = 'a Lwt.t
   let return = Lwt.return
   let bind = Lwt.bind
diff --git a/smtp.obuild b/smtp.obuild
index f9d796e..a99f9e9 100644
--- a/smtp.obuild
+++ b/smtp.obuild
@@ -12,10 +12,22 @@ library smtp
 
 library smtp_unix
         modules: Smtp_unix
-        builddepends: smtp
+        builddepends: smtp, unix
         src-dir: unix
 
 library smtp_lwt
         modules: Smtp_lwt
         builddepends: smtp, lwt, lwt.unix
         src-dir: lwt
+
+test test_lwt
+        mainis: test_lwt.ml
+        builddepends: smtp_lwt
+        src-dir: test
+        rundir: test
+
+test test_unix
+        mainis: test_unix.ml
+        builddepends: smtp_unix
+        src-dir: test
+        rundir: test
diff --git a/test/test_lwt.ml b/test/test_lwt.ml
new file mode 100644
index 0000000..5a073e7
--- /dev/null
+++ b/test/test_lwt.ml
@@ -0,0 +1,11 @@
+open Smtp_lwt
+
+let () = match Lwt_main.run
+  (sendmail
+     ~port:"2525"
+     ~name:"localhost"
+     ~from:Addr.(of_string "vb@luminar.eu.org")
+     ~to_:[Addr.(of_string "vb@luminar.eu.org")]
+     ~body:"Bleh" ()) with
+    | `Ok (code, msg) -> Printf.printf "OK %d %s\n" code msg
+    | `Failure (code, msg) -> Printf.eprintf "Failure %d %s\n" code msg
diff --git a/test/test_unix.ml b/test/test_unix.ml
new file mode 100644
index 0000000..3633939
--- /dev/null
+++ b/test/test_unix.ml
@@ -0,0 +1,11 @@
+open Smtp_unix
+
+let () = match
+    (sendmail
+       ~port:"2525"
+       ~name:"localhost"
+       ~from:Addr.(of_string "vb@luminar.eu.org")
+       ~to_:[Addr.(of_string "vb@luminar.eu.org")]
+       ~body:"Bleh" ()) with
+      | `Ok (code, msg) -> Printf.printf "OK %d %s\n" code msg
+      | `Failure (code, msg) -> Printf.eprintf "Failure %d %s\n" code msg
diff --git a/unix/smtp_unix.ml b/unix/smtp_unix.ml
index 9679756..314796e 100644
--- a/unix/smtp_unix.ml
+++ b/unix/smtp_unix.ml
@@ -1,4 +1,4 @@
-module IO : Smtp.IO = struct
+module IO = struct
   type 'a t = 'a
   let return v = v
   let bind v f = f v