diff --git a/.travis.yml b/.travis.yml
index caa9269..9aaf7cb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,11 +1,14 @@
 language: c
-sudo: require
-install: wget https://raw.githubusercontent.com/ocaml/ocaml-ci-scripts/master/.travis-docker.sh
+sudo: false
+services:
+  - docker
+install:
+  - wget https://raw.githubusercontent.com/ocaml/ocaml-ci-scripts/master/.travis-docker.sh
 script: bash -ex .travis-docker.sh
 env:
   global:
     - OCAML_VERSION=4.04.2
-    - DISTRO=debian-stable
+    - DISTRO=centos-7
     - PACKAGE=xapi-nbd
   matrix:
     - BASE_REMOTE=git://github.com/xapi-project/xs-opam
diff --git a/lib/vbd_store.ml b/lib/vbd_store.ml
index 5e688cd..1829036 100644
--- a/lib/vbd_store.ml
+++ b/lib/vbd_store.ml
@@ -21,7 +21,7 @@ module Make(Config : sig
     Lwt.catch
       (fun () -> Lwt_unix.mkdir vbd_list_dir 0o755)
       (function
-        | Unix.(Unix_error (EEXIST, "mkdir", dir)) when dir = vbd_list_dir -> Lwt.return_unit
+        | Unix.Unix_error (EEXIST, "mkdir", dir) when dir = vbd_list_dir -> Lwt.return_unit
         | e ->
           (* In any other case we let the client fail. In this case the user/admin should go and fix the root cause of the issue *)
           log_and_reraise_error ("Failed to create directory " ^ vbd_list_dir) e
@@ -38,7 +38,7 @@ module Make(Config : sig
         Lwt.catch
           (fun () -> Lwt_io.lines_of_file vbd_list_file |> Lwt_stream.to_list)
           (function
-            | Unix.(Unix_error (ENOENT, "open", file)) when file = vbd_list_file -> Lwt.return []
+            | Unix.Unix_error (ENOENT, "open", file) when file = vbd_list_file -> Lwt.return []
             | e ->
               (* In any other case we let the client fail. In this case the user/admin should go and fix the root cause of the issue *)
               log_and_reraise_error ("Failed to read file " ^ vbd_list_file) e
diff --git a/src/cleanup.ml b/src/cleanup.ml
index c11cc87..3c81b4d 100644
--- a/src/cleanup.ml
+++ b/src/cleanup.ml
@@ -29,7 +29,7 @@ module VBD = struct
     let vbds_to_clean_up = ref StringSet.empty
     let vbds_to_clean_up_mutex = Lwt_mutex.create ()
 
-    let with_tracking rpc session_id vbd f =
+    let with_tracking vbd f =
       Lwt_mutex.with_lock vbds_to_clean_up_mutex (fun () -> Lwt.wrap (fun () ->
           vbds_to_clean_up := StringSet.add (API.Ref.string_of vbd) !vbds_to_clean_up))
       >>= fun () ->
@@ -105,7 +105,7 @@ module VBD = struct
     Xen_api.VBD.create ~rpc ~session_id ~vM ~vDI ~userdevice:"autodetect" ~bootable:false ~mode ~_type:`Disk ~unpluggable:true ~empty:false ~other_config:[] ~qos_algorithm_type:"" ~qos_algorithm_params:[]
     >>= fun vbd ->
     Persistent.with_tracking rpc session_id vbd (fun () ->
-        Runtime.with_tracking rpc session_id vbd (fun () ->
+        Runtime.with_tracking vbd (fun () ->
             Lwt.finalize
               (fun () ->
                  Lwt_log.notice_f "Plugging VBD %s" (API.Ref.string_of vbd) >>= fun () ->
diff --git a/src/main.ml b/src/main.ml
index 38a98ad..6e7ae1c 100644
--- a/src/main.ml
+++ b/src/main.ml
@@ -120,7 +120,7 @@ let main port certfile ciphersuites =
          Lwt_log.notice "Setting up server socket" >>= fun () ->
          Lwt_unix.setsockopt sock Lwt_unix.SO_REUSEADDR true;
          let sockaddr = Lwt_unix.ADDR_INET(Unix.inet_addr_any, port) in
-         Lwt_unix.bind sock sockaddr;
+         Lwt_unix.bind sock sockaddr >>= fun () ->
          Lwt_unix.listen sock 5;
          Lwt_log.notice "Listening for incoming connections" >>= fun () ->
 
@@ -165,13 +165,14 @@ let main port certfile ciphersuites =
       (ignore_exn_delayed (fun () -> Lwt_unix.close sock))
   in
   (* Log unexpected exceptions *)
-  Lwt_main.run
+  let () = Lwt_main.run
     (Lwt.catch t
        (fun e ->
           Lwt_log.fatal_f "Caught unexpected exception: %s" (Printexc.to_string e) >>= fun () ->
           Lwt.fail e
        )
-    );
+    )
+  in
 
   `Ok ()