diff --git a/src/fat.ml b/src/fat.ml
index f06a829c..f2fad9db 100644
--- a/src/fat.ml
+++ b/src/fat.ml
@@ -13,6 +13,11 @@ type entry = Mfat.entry = {
   size: int32;
 }
 
+let create blk =
+  match Fat.create blk with
+  | Error (`Msg e) -> Fmt.failwith "FAT file system failure: %s." e
+  | Ok fs -> fs
+
 type t = Mkernel.Block.t Mfat.t
 
 module type FS = sig
diff --git a/src/mte.ml b/src/mte.ml
index 4f06e81f..a13c7d28 100644
--- a/src/mte.ml
+++ b/src/mte.ml
@@ -73,12 +73,13 @@ let () =
     let rng () = Mirage_crypto_rng_mkernel.initialize (module RNG) in
     Mkernel.map rng Mkernel.[]
   in
-  let storage = Mkernel.storage ~name:"storage" in
+  let storage = Mkernel.block "storage" in
   let service =
     let ipv4 = Ipaddr.V4.Prefix.of_string_exn "10.0.0.2/24" in
     Mnet.stack ~name:"service" ipv4
   in
-  Mkernel.(run [ rng; storage; service ]) @@ fun rng fs (stack, tcp, udp) () ->
+  Mkernel.(run [ rng; storage; service ])
+  @@ fun rng storage (stack, tcp, udp) () ->
   let@ () = fun () -> Mirage_crypto_rng_mkernel.kill rng in
   let@ () = fun () -> Mnet.kill stack in
   let hed, he = Mnet_happy_eyeballs.create tcp in
@@ -88,20 +89,10 @@ let () =
   let@ () = fun () -> Mnet_dns.Transport.kill t in
   Caqti_miou.Switch.run @@ fun sw ->
   (* -- *)
+  let fs = Fat.create storage in
   let env = Env.{ sw; stack; tcp; dns; fs } in
   let devices = Vifu.Devices.[ Global.db_conn; Global.keys ] in
   let cfg = Vifu.Config.v Config.Exchange.port in
-  Vifu.run ~cfg ~devices tcp routes env
-
-(*
-  Miou_unix.run @@ fun () ->
-  Caqti_miou.Switch.run @@ fun caqti_switch ->
-  let env : Devices.env =
-    { caqti_switch; db_uri= Config.Exchangedb_postgres.config }
-  in
-  let devices = Vifu.Devices.[ Devices.db_connection; Devices.keys ] in
-  let middlewares = Vifu.Middlewares.[] in
   Logs.info (fun m ->
       m ~tags:(Util.Log_reporter.detail "...") "Starting MTE server");
-  Vifu.run ~cfg ~devices ~middlewares routes env
-  *)
+  Vifu.run ~cfg ~devices tcp routes env