diff --git a/bench/irmin-pack/dune b/bench/irmin-pack/dune
index ae902eaf69..b95a7cc624 100644
--- a/bench/irmin-pack/dune
+++ b/bench/irmin-pack/dune
@@ -15,6 +15,7 @@
   repr
   ppx_repr
   bench_common
+  mtime
   rusage))
 
 (library
diff --git a/bench/irmin-pack/trace_collection.ml b/bench/irmin-pack/trace_collection.ml
index 5bc65110e4..20b7b03209 100644
--- a/bench/irmin-pack/trace_collection.ml
+++ b/bench/irmin-pack/trace_collection.ml
@@ -152,10 +152,7 @@ module Make_stat (Store : Irmin.Generic_key.KV) = struct
         }
 
     let now () =
-      Mtime_clock.now ()
-      |> Mtime.to_uint64_ns
-      |> Int64.to_float
-      |> ( *. ) Mtime.ns_to_s
+      Mtime_clock.now () |> Mtime.to_uint64_ns |> Int64.to_float |> ( *. ) 1e-9
 
     let create store_path prev_merge_durations =
       Def.
diff --git a/irmin-test.opam b/irmin-test.opam
index ba7eeed54b..bf35ef36c2 100644
--- a/irmin-test.opam
+++ b/irmin-test.opam
@@ -17,7 +17,7 @@ depends: [
   "ppx_irmin"    {= version}
   "ocaml"        {>= "4.02.3"}
   "dune"         {>= "2.9.0"}
-  "alcotest"     {>= "1.5.0"}
+  "alcotest-lwt" {>= "1.5.0"}
   "mtime"        {>= "1.0.0"}
   "astring"
   "fmt"
@@ -30,7 +30,6 @@ depends: [
   "metrics" {>= "0.2.0"}
   "hex" {with-test & >= "1.4.0"}
   "vector" {with-test & >= "1.0.0"}
-  "alcotest-lwt" {with-test & >= "1.5.0"}
 ]
 
 synopsis: "Irmin test suite"
diff --git a/src/irmin-test/common.ml b/src/irmin-test/common.ml
index 6d35c1f18a..01436177bb 100644
--- a/src/irmin-test/common.ml
+++ b/src/irmin-test/common.ml
@@ -130,7 +130,7 @@ module Suite = struct
 end
 
 module type Store_tests = functor (S : Generic_key) -> sig
-  val tests : (string * (Suite.t -> unit -> unit)) list
+  val tests : (string * (Suite.t -> unit -> unit Lwt.t)) list
 end
 
 module Make_helpers (S : Generic_key) = struct
@@ -215,48 +215,47 @@ module Make_helpers (S : Generic_key) = struct
   let run (x : Suite.t) test =
     let repo_ptr = ref None in
     let config_ptr = ref None in
-    Lwt_main.run
-      (Lwt.catch
-         (fun () ->
-           let module Conf = Irmin.Backend.Conf in
-           let generate_random_root config =
-             let id = Random.int 100 |> string_of_int in
-             let root_value =
-               match Conf.find_root config with
-               | None -> "test_" ^ id
-               | Some v -> v ^ "_" ^ id
-             in
-             let root_key = Conf.(root (spec config)) in
-             Conf.add config root_key root_value
-           in
-           let config = generate_random_root x.config in
-           config_ptr := Some config;
-           let* () = x.init ~config in
-           let* repo = S.Repo.v config in
-           repo_ptr := Some repo;
-           let* () = test repo in
-           let* () =
-             (* [test] might have already closed the repo. That
-                [ignore_thunk_errors] shall be removed as soon as all stores
-                support double closes. *)
-             ignore_thunk_errors (fun () -> S.Repo.close repo)
-           in
-           x.clean ~config)
-         (fun exn ->
-           (* [test] failed, attempt an errorless cleanup and forward the right
-              backtrace to the user. *)
-           let bt = Printexc.get_raw_backtrace () in
-           let* () =
-             match !repo_ptr with
-             | Some repo -> ignore_thunk_errors (fun () -> S.Repo.close repo)
-             | None -> Lwt.return_unit
-           in
-           let+ () =
-             match !config_ptr with
-             | Some config -> ignore_thunk_errors (fun () -> x.clean ~config)
-             | None -> Lwt.return_unit
-           in
-           Printexc.raise_with_backtrace exn bt))
+    Lwt.catch
+      (fun () ->
+        let module Conf = Irmin.Backend.Conf in
+        let generate_random_root config =
+          let id = Random.int 100 |> string_of_int in
+          let root_value =
+            match Conf.find_root config with
+            | None -> "test_" ^ id
+            | Some v -> v ^ "_" ^ id
+          in
+          let root_key = Conf.(root (spec config)) in
+          Conf.add config root_key root_value
+        in
+        let config = generate_random_root x.config in
+        config_ptr := Some config;
+        let* () = x.init ~config in
+        let* repo = S.Repo.v config in
+        repo_ptr := Some repo;
+        let* () = test repo in
+        let* () =
+          (* [test] might have already closed the repo. That
+             [ignore_thunk_errors] shall be removed as soon as all stores
+             support double closes. *)
+          ignore_thunk_errors (fun () -> S.Repo.close repo)
+        in
+        x.clean ~config)
+      (fun exn ->
+        (* [test] failed, attempt an errorless cleanup and forward the right
+           backtrace to the user. *)
+        let bt = Printexc.get_raw_backtrace () in
+        let* () =
+          match !repo_ptr with
+          | Some repo -> ignore_thunk_errors (fun () -> S.Repo.close repo)
+          | None -> Lwt.return_unit
+        in
+        let+ () =
+          match !config_ptr with
+          | Some config -> ignore_thunk_errors (fun () -> x.clean ~config)
+          | None -> Lwt.return_unit
+        in
+        Printexc.raise_with_backtrace exn bt)
 end
 
 let filter_src src =
@@ -319,3 +318,7 @@ let check_raises_lwt msg exn (type a) (f : unit -> a Lwt.t) =
             msg (Printexc.to_string exn) (Printexc.to_string e))
 
 module T = Irmin.Type
+
+module type Sleep = sig
+  val sleep : float -> unit Lwt.t
+end
diff --git a/src/irmin-test/dune b/src/irmin-test/dune
index 7c5d149267..7fbcdc1c45 100644
--- a/src/irmin-test/dune
+++ b/src/irmin-test/dune
@@ -5,14 +5,13 @@
  (preprocess
   (pps ppx_irmin.internal))
  (libraries
-  alcotest
+  alcotest-lwt
   astring
   fmt
   irmin
   jsonm
   logs.fmt
   lwt
-  lwt.unix
   mtime
   mtime.clock.os)
  (instrumentation
diff --git a/src/irmin-test/irmin_test.mli b/src/irmin-test/irmin_test.mli
index d5aa465ecf..52fa646d48 100644
--- a/src/irmin-test/irmin_test.mli
+++ b/src/irmin-test/irmin_test.mli
@@ -65,9 +65,10 @@ module Store : sig
     string ->
     ?slow:bool ->
     ?random_seed:int ->
-    misc:unit Alcotest.test list ->
+    sleep:(float -> unit Lwt.t) ->
+    misc:unit Alcotest_lwt.test list ->
     (Alcotest.speed_level * Suite.t) list ->
-    unit
+    unit Lwt.t
 end
 
 module Node = Node
diff --git a/src/irmin-test/store.ml b/src/irmin-test/store.ml
index de040fb062..7d2a84d018 100644
--- a/src/irmin-test/store.ml
+++ b/src/irmin-test/store.ml
@@ -2412,9 +2412,9 @@ module Make (S : Generic_key) = struct
       S.Backend.Repo.close repo
     in
     (* Test collisions with the empty node (and its commit), *)
-    run x (test @@ fun () -> S.Tree.empty () |> Lwt.return);
+    let* () = run x (test @@ fun () -> S.Tree.empty () |> Lwt.return) in
     (* with a length one node, *)
-    run x (test @@ fun () -> add_entries (S.Tree.empty ()) 1);
+    run x (test @@ fun () -> add_entries (S.Tree.empty ()) 1) >>= fun () ->
     (* and with a length >256 node (which is the threshold for unstable inodes
        in irmin pack). *)
     run x (test @@ fun () -> add_entries (S.Tree.empty ()) 260)
@@ -2427,11 +2427,14 @@ let suite' l ?(prefix = "") (_, x) =
 
 let when_ b x = if b then x else []
 
-let suite (speed, x) =
+let suite sleep (speed, x) =
   let (module S) = Suite.store_generic_key x in
+  let module Zzz = struct
+    let sleep = sleep
+  end in
   let module T = Make (S) in
   let module T_graph = Store_graph.Make (S) in
-  let module T_watch = Store_watch.Make (Log) (S) in
+  let module T_watch = Store_watch.Make (Log) (Zzz) (S) in
   let with_tree_enabled =
     (* Disabled for flakiness. See https://github.com/mirage/irmin/issues/1090. *)
     not
@@ -2494,7 +2497,7 @@ let slow_suite (speed, x) =
     ]
     (speed, x)
 
-let run name ?(slow = false) ?random_seed ~misc tl =
+let run name ?(slow = false) ?random_seed ~sleep ~misc tl =
   let () =
     match random_seed with
     | Some x -> Random.init x
@@ -2503,6 +2506,6 @@ let run name ?(slow = false) ?random_seed ~misc tl =
   Printexc.record_backtrace true;
   (* Ensure that failures occuring in async lwt threads are raised. *)
   (Lwt.async_exception_hook := fun exn -> raise exn);
-  let tl1 = List.map suite tl in
+  let tl1 = List.map (suite sleep) tl in
   let tl1 = if slow then tl1 @ List.map slow_suite tl else tl1 in
-  Alcotest.run name (misc @ tl1)
+  Alcotest_lwt.run name (misc @ tl1)
diff --git a/src/irmin-test/store.mli b/src/irmin-test/store.mli
index 6cf39bfb5e..57aeeb89dc 100644
--- a/src/irmin-test/store.mli
+++ b/src/irmin-test/store.mli
@@ -18,6 +18,7 @@ val run :
   string ->
   ?slow:bool ->
   ?random_seed:int ->
-  misc:unit Alcotest.test list ->
+  sleep:(float -> unit Lwt.t) ->
+  misc:unit Alcotest_lwt.test list ->
   (Alcotest.speed_level * Common.t) list ->
-  unit
+  unit Lwt.t
diff --git a/src/irmin-test/store_watch.ml b/src/irmin-test/store_watch.ml
index 204b42fa87..eb14afc329 100644
--- a/src/irmin-test/store_watch.ml
+++ b/src/irmin-test/store_watch.ml
@@ -17,12 +17,16 @@
 open! Import
 open Common
 
-module Make (Log : Logs.LOG) (S : Generic_key) = struct
+module type Sleep = sig
+  val sleep : float -> unit Lwt.t
+end
+
+module Make (Log : Logs.LOG) (Zzz : Sleep) (S : Generic_key) = struct
   include Common.Make_helpers (S)
 
   let sleep ?(sleep_t = 0.01) () =
     let sleep_t = min sleep_t 1. in
-    Lwt.pause () >>= fun () -> Lwt_unix.sleep sleep_t
+    Lwt.pause () >>= fun () -> Zzz.sleep sleep_t
 
   let now_s () = Mtime.Span.to_s (Mtime_clock.elapsed ())
 
@@ -193,9 +197,7 @@ module Make (Log : Logs.LOG) (S : Generic_key) = struct
 
       let process ?sleep_t t head =
         let* () =
-          match sleep_t with
-          | None -> Lwt.return_unit
-          | Some s -> Lwt_unix.sleep s
+          match sleep_t with None -> Lwt.return_unit | Some s -> Zzz.sleep s
         in
         let () =
           match head with
diff --git a/src/irmin-test/store_watch.mli b/src/irmin-test/store_watch.mli
index 5baae0e907..52f253c7bb 100644
--- a/src/irmin-test/store_watch.mli
+++ b/src/irmin-test/store_watch.mli
@@ -14,4 +14,4 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  *)
 
-module Make (_ : Logs.LOG) : Common.Store_tests
+module Make (_ : Logs.LOG) (_ : Common.Sleep) : Common.Store_tests
diff --git a/test/irmin-chunk/test.ml b/test/irmin-chunk/test.ml
index 94c8d9df41..eef06a60f2 100644
--- a/test/irmin-chunk/test.ml
+++ b/test/irmin-chunk/test.ml
@@ -22,7 +22,7 @@ let key_t : Test_chunk.Key.t Alcotest.testable = (module Test_chunk.Key)
 let value_t : Test_chunk.Value.t Alcotest.testable = (module Test_chunk.Value)
 
 let run f () =
-  Lwt_main.run (f ());
+  let+ () = f () in
   flush stderr;
   flush stdout
 
@@ -77,5 +77,7 @@ let stable =
     ] )
 
 let () =
-  Irmin_test.Store.run "irmin-chunk" ~slow:true ~misc:[ simple; stable ]
-    [ (`Quick, Test_chunk.suite) ]
+  Lwt_main.run
+  @@ Irmin_test.Store.run "irmin-chunk" ~slow:true ~misc:[ simple; stable ]
+       ~sleep:Lwt_unix.sleep
+       [ (`Quick, Test_chunk.suite) ]
diff --git a/test/irmin-fs/dune b/test/irmin-fs/dune
index 8a25710472..87614dbcb5 100644
--- a/test/irmin-fs/dune
+++ b/test/irmin-fs/dune
@@ -11,7 +11,7 @@
 (executable
  (name test)
  (modules test)
- (libraries alcotest irmin irmin-test test_fs))
+ (libraries alcotest lwt.unix irmin irmin-test test_fs))
 
 (executable
  (name test_unix)
diff --git a/test/irmin-fs/test.ml b/test/irmin-fs/test.ml
index daa5b5fd09..2ab8c18fce 100644
--- a/test/irmin-fs/test.ml
+++ b/test/irmin-fs/test.ml
@@ -15,5 +15,6 @@
  *)
 
 let () =
-  Irmin_test.Store.run "irmin-fs" ~slow:true ~misc:[]
-    [ (`Quick, Test_fs.suite) ]
+  Lwt_main.run
+  @@ Irmin_test.Store.run "irmin-fs" ~slow:true ~misc:[] ~sleep:Lwt_unix.sleep
+       [ (`Quick, Test_fs.suite) ]
diff --git a/test/irmin-fs/test_unix.ml b/test/irmin-fs/test_unix.ml
index ab79823908..1bc071b639 100644
--- a/test/irmin-fs/test_unix.ml
+++ b/test/irmin-fs/test_unix.ml
@@ -15,5 +15,7 @@
  *)
 
 let () =
-  Irmin_test.Store.run "irmin-fs.unix" ~slow:false ~misc:[]
-    [ (`Quick, Test_fs_unix.suite) ]
+  Lwt_main.run
+  @@ Irmin_test.Store.run "irmin-fs.unix" ~slow:false ~sleep:Lwt_unix.sleep
+       ~misc:[]
+       [ (`Quick, Test_fs_unix.suite) ]
diff --git a/test/irmin-git/test.ml b/test/irmin-git/test.ml
index 3cf601fc60..154b15db4c 100644
--- a/test/irmin-git/test.ml
+++ b/test/irmin-git/test.ml
@@ -17,5 +17,6 @@
 let misc = [ ("misc", Test_git.(misc mem)) ]
 
 let () =
-  Irmin_test.Store.run "irmin-git" ~slow:true ~misc
-    [ (`Quick, Test_git.suite); (`Quick, Test_git.suite_generic) ]
+  Lwt_main.run
+  @@ Irmin_test.Store.run "irmin-git" ~slow:true ~misc ~sleep:Lwt_unix.sleep
+       [ (`Quick, Test_git.suite); (`Quick, Test_git.suite_generic) ]
diff --git a/test/irmin-git/test_git.ml b/test/irmin-git/test_git.ml
index bf00055c62..1fae8fa6cc 100644
--- a/test/irmin-git/test_git.ml
+++ b/test/irmin-git/test_git.ml
@@ -228,14 +228,13 @@ let misc (module S : G) =
   let s = (module S : S) in
   let g = (module S : G) in
   let generic = (module Generic (Irmin.Contents.String) : S) in
-  let run f x () = Lwt_main.run (f x) in
   [
-    ("Testing sort order", `Quick, run test_sort_order s);
-    ("Testing sort order (generic)", `Quick, run test_sort_order generic);
-    ("Testing listing refs", `Quick, run test_list_refs g);
-    ("git -> mem", `Quick, run test_import_export s);
-    ("git blobs", `Quick, run test_blobs s);
-    ("git blobs of generic", `Quick, run test_blobs s);
+    ("Testing sort order", `Quick, fun () -> test_sort_order s);
+    ("Testing sort order (generic)", `Quick, fun () -> test_sort_order generic);
+    ("Testing listing refs", `Quick, fun () -> test_list_refs g);
+    ("git -> mem", `Quick, fun () -> test_import_export s);
+    ("git blobs", `Quick, fun () -> test_blobs s);
+    ("git blobs of generic", `Quick, fun () -> test_blobs s);
   ]
 
 let mem = (module Mem (Irmin.Contents.String) : G)
diff --git a/test/irmin-git/test_git.mli b/test/irmin-git/test_git.mli
index 8956cfd27a..6191323f9a 100644
--- a/test/irmin-git/test_git.mli
+++ b/test/irmin-git/test_git.mli
@@ -29,5 +29,5 @@ module type G = sig
   module Git : Irmin_git.G
 end
 
-val misc : (module G) -> unit Alcotest.test_case list
+val misc : (module G) -> unit Alcotest_lwt.test_case list
 val mem : (module G)
diff --git a/test/irmin-git/test_unix.ml b/test/irmin-git/test_unix.ml
index bbce7711e8..9e3157ec8f 100644
--- a/test/irmin-git/test_unix.ml
+++ b/test/irmin-git/test_unix.ml
@@ -16,4 +16,8 @@
 
 let misc = [ ("misc", Test_git.misc Test_git_unix.store) ]
 let suites = [ (`Quick, Test_git_unix.suite) ]
-let () = Irmin_test.Store.run "irmin-git.unix" ~misc ~slow:false suites
+
+let () =
+  Lwt_main.run
+  @@ Irmin_test.Store.run "irmin-git.unix" ~misc ~slow:false
+       ~sleep:Lwt_unix.sleep suites
diff --git a/test/irmin-http/test.ml b/test/irmin-http/test.ml
index 37955e1537..7f7f4950e2 100644
--- a/test/irmin-http/test.ml
+++ b/test/irmin-http/test.ml
@@ -16,4 +16,5 @@
 
 let () =
   Test_http.(with_server servers) (fun () ->
-      Irmin_test.Store.run "irmin-http" ~misc:[] Test_http.(suites servers))
+      Irmin_test.Store.run "irmin-http" ~misc:[] ~sleep:Lwt_unix.sleep
+        Test_http.(suites servers))
diff --git a/test/irmin-http/test_http.ml b/test/irmin-http/test_http.ml
index 2af8264611..999675740a 100644
--- a/test/irmin-http/test_http.ml
+++ b/test/irmin-http/test_http.ml
@@ -233,6 +233,6 @@ let with_server servers f =
     let id = int_of_string Sys.argv.(3) in
     Logs.set_reporter (Irmin_test.reporter ~prefix:"S" ());
     serve servers n id)
-  else f ()
+  else Lwt_main.run (f ())
 
 type test = Alcotest.speed_level * Irmin_test.Suite.t
diff --git a/test/irmin-http/test_http.mli b/test/irmin-http/test_http.mli
index daf5949090..f9541ffbf1 100644
--- a/test/irmin-http/test_http.mli
+++ b/test/irmin-http/test_http.mli
@@ -18,4 +18,4 @@ type test = Alcotest.speed_level * Irmin_test.Suite.t
 
 val servers : test list
 val suites : test list -> test list
-val with_server : test list -> (unit -> unit) -> unit
+val with_server : test list -> (unit -> unit Lwt.t) -> unit
diff --git a/test/irmin-mem/dune b/test/irmin-mem/dune
index 89e02a5167..1f548b95c1 100644
--- a/test/irmin-mem/dune
+++ b/test/irmin-mem/dune
@@ -6,7 +6,7 @@
 (executable
  (name test)
  (modules test)
- (libraries alcotest irmin-test test_mem))
+ (libraries alcotest lwt.unix irmin-test test_mem))
 
 (rule
  (alias runtest)
diff --git a/test/irmin-mem/test.ml b/test/irmin-mem/test.ml
index 3f03884961..e2d99e032f 100644
--- a/test/irmin-mem/test.ml
+++ b/test/irmin-mem/test.ml
@@ -15,5 +15,6 @@
  *)
 
 let () =
-  Irmin_test.Store.run "irmin-mem" ~slow:true ~misc:[]
-    [ (`Quick, Test_mem.suite) ]
+  Lwt_main.run
+  @@ Irmin_test.Store.run "irmin-mem" ~slow:true ~misc:[] ~sleep:Lwt_unix.sleep
+       [ (`Quick, Test_mem.suite) ]
diff --git a/test/irmin-pack/multiple_instances.ml b/test/irmin-pack/multiple_instances.ml
index d7343f9ee6..93f9904a20 100644
--- a/test/irmin-pack/multiple_instances.ml
+++ b/test/irmin-pack/multiple_instances.ml
@@ -106,9 +106,7 @@ let ro_reload_after_close () =
   binding (check_binding ro c1) >>= fun () -> S.Repo.close ro
 
 let tests =
-  let tc name test =
-    Alcotest.test_case name `Quick (fun () -> Lwt_main.run (test ()))
-  in
+  let tc name test = Alcotest_lwt.test_case name `Quick (fun _switch -> test) in
   [
     tc "Test open ro after rw closed" open_ro_after_rw_closed;
     tc "Test ro reload after add" ro_reload_after_add;
diff --git a/test/irmin-pack/multiple_instances.mli b/test/irmin-pack/multiple_instances.mli
index 2b40d2f891..4acc26805b 100644
--- a/test/irmin-pack/multiple_instances.mli
+++ b/test/irmin-pack/multiple_instances.mli
@@ -14,4 +14,4 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  *)
 
-val tests : unit Alcotest.test_case list
+val tests : unit Alcotest_lwt.test_case list
diff --git a/test/irmin-pack/test.ml b/test/irmin-pack/test.ml
index 5ff13df8d8..8b35dbfa8f 100644
--- a/test/irmin-pack/test.ml
+++ b/test/irmin-pack/test.ml
@@ -15,5 +15,7 @@
  *)
 
 let () =
-  Irmin_test.Store.run "irmin-pack" ~misc:Test_pack.misc
-    (List.map (fun s -> (`Quick, s)) Test_pack.suite)
+  Lwt_main.run
+  @@ Irmin_test.Store.run "irmin-pack" ~misc:Test_pack.misc
+       ~sleep:Lwt_unix.sleep
+       (List.map (fun s -> (`Quick, s)) Test_pack.suite)
diff --git a/test/irmin-pack/test_existing_stores.ml b/test/irmin-pack/test_existing_stores.ml
index 3d99325105..aaacec2977 100644
--- a/test/irmin-pack/test_existing_stores.ml
+++ b/test/irmin-pack/test_existing_stores.ml
@@ -216,10 +216,10 @@ end
 
 let tests =
   [
-    Alcotest.test_case "Test index reconstruction" `Quick (fun () ->
-        Lwt_main.run (Test_reconstruct.test_reconstruct ()));
-    Alcotest.test_case "Test integrity check" `Quick (fun () ->
-        Lwt_main.run (Test_corrupted_stores.test ()));
-    Alcotest.test_case "Test integrity check for inodes" `Quick (fun () ->
-        Lwt_main.run (Test_corrupted_inode.test ()));
+    Alcotest_lwt.test_case "Test index reconstruction" `Quick (fun _switch ->
+        Test_reconstruct.test_reconstruct);
+    Alcotest_lwt.test_case "Test integrity check" `Quick (fun _switch ->
+        Test_corrupted_stores.test);
+    Alcotest_lwt.test_case "Test integrity check for inodes" `Quick
+      (fun _switch -> Test_corrupted_inode.test);
   ]
diff --git a/test/irmin-pack/test_existing_stores.mli b/test/irmin-pack/test_existing_stores.mli
index 2b40d2f891..4acc26805b 100644
--- a/test/irmin-pack/test_existing_stores.mli
+++ b/test/irmin-pack/test_existing_stores.mli
@@ -14,4 +14,4 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  *)
 
-val tests : unit Alcotest.test_case list
+val tests : unit Alcotest_lwt.test_case list
diff --git a/test/irmin-pack/test_flush_reload.ml b/test/irmin-pack/test_flush_reload.ml
index 9cd6ff86f6..31e4db6351 100644
--- a/test/irmin-pack/test_flush_reload.ml
+++ b/test/irmin-pack/test_flush_reload.ml
@@ -247,8 +247,8 @@ let test_reload () =
 
 let tests =
   [
-    Alcotest.test_case "Reload during flush stages" `Quick (fun () ->
-        Lwt_main.run (test_flush ()));
-    Alcotest.test_case "Flush during reload stages" `Quick (fun () ->
-        Lwt_main.run (test_reload ()));
+    Alcotest_lwt.test_case "Reload during flush stages" `Quick
+      (fun _switch () -> test_flush ());
+    Alcotest_lwt.test_case "Flush during reload stages" `Quick
+      (fun _switch () -> test_reload ());
   ]
diff --git a/test/irmin-pack/test_gc.ml b/test/irmin-pack/test_gc.ml
index 7f1a896038..ae85ca34af 100644
--- a/test/irmin-pack/test_gc.ml
+++ b/test/irmin-pack/test_gc.ml
@@ -30,7 +30,7 @@ let fresh_name =
     let name = Filename.concat test_dir ("test-gc" ^ string_of_int !c) in
     name
 
-let tc name f = Alcotest.test_case name `Quick (fun () -> Lwt_main.run (f ()))
+let tc name f = Alcotest_lwt.test_case name `Quick (fun _switch () -> f ())
 
 include struct
   module S = struct
diff --git a/test/irmin-pack/test_gc.mli b/test/irmin-pack/test_gc.mli
index a00e5547f3..edf8103aed 100644
--- a/test/irmin-pack/test_gc.mli
+++ b/test/irmin-pack/test_gc.mli
@@ -15,9 +15,9 @@
  *)
 
 module Blocking_gc : sig
-  val tests : unit Alcotest.test_case list
+  val tests : unit Alcotest_lwt.test_case list
 end
 
 module Concurrent_gc : sig
-  val tests : unit Alcotest.test_case list
+  val tests : unit Alcotest_lwt.test_case list
 end
diff --git a/test/irmin-pack/test_hashes.ml b/test/irmin-pack/test_hashes.ml
index 4e6ea213e8..0aecf77c8e 100644
--- a/test/irmin-pack/test_hashes.ml
+++ b/test/irmin-pack/test_hashes.ml
@@ -311,9 +311,7 @@ module Test_V1 = struct
 end
 
 let tests =
-  let tc name f =
-    Alcotest.test_case name `Quick (fun () -> Lwt_main.run (f ()))
-  in
+  let tc name f = Alcotest_lwt.test_case name `Quick (fun _switch -> f) in
   [
     tc "contents hash" Test_tezos_conf.contents_hash;
     tc "inode_values hash" Test_tezos_conf.inode_values_hash;
diff --git a/test/irmin-pack/test_hashes.mli b/test/irmin-pack/test_hashes.mli
index 3e8b1f82b6..5502f37745 100644
--- a/test/irmin-pack/test_hashes.mli
+++ b/test/irmin-pack/test_hashes.mli
@@ -14,7 +14,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  *)
 
-val tests : unit Alcotest.test_case list
+val tests : unit Alcotest_lwt.test_case list
 
 val check_iter :
   string ->
diff --git a/test/irmin-pack/test_inode.ml b/test/irmin-pack/test_inode.ml
index aa194b22a7..e261e98723 100644
--- a/test/irmin-pack/test_inode.ml
+++ b/test/irmin-pack/test_inode.ml
@@ -808,7 +808,7 @@ module Child_ordering = struct
     assert (chosen_bit = 0 || chosen_bit = 1);
     chosen_bit
 
-  let test_seeded_hash () =
+  let test_seeded_hash _switch () =
     let entries = Irmin_tezos.Conf.entries in
     let reference ~depth step =
       abs (Step.short_hash ~seed:depth step) mod entries
@@ -825,7 +825,8 @@ module Child_ordering = struct
       let step = random_string 8 and depth = Random.int 10 in
       let expected = reference ~depth step in
       check_child_index __POS__ (module Order) ~expected ~step ~depth
-    done
+    done;
+    Lwt.return_unit
 
   let hash_bits_max_depth ~log2_entries =
     (* For a given [depth], the final bit of the corresponding index is at
@@ -838,7 +839,7 @@ module Child_ordering = struct
     in
     aux 0
 
-  let test_hash_bits () =
+  let test_hash_bits _switch () =
     (* [entries] is required to be a power of 2 greater than 1 and less than
        2048, so we test every possible value here: *)
     for log2_entries = 1 to 10 do
@@ -875,9 +876,10 @@ module Child_ordering = struct
           (module Order)
           ~step ~depth:(max_depth + 1)
       done
-    done
+    done;
+    Lwt.return_unit
 
-  let test_custom () =
+  let test_custom _switch () =
     let entries = 16 in
     let square_index ~depth step =
       let a = depth and b = int_of_string (Bytes.unsafe_to_string step) in
@@ -887,12 +889,13 @@ module Child_ordering = struct
     check_child_index __POS__ (module Order) ~depth:1 ~step:"1" ~expected:1;
     check_child_index __POS__ (module Order) ~depth:2 ~step:"2" ~expected:4;
     check_child_index __POS__ (module Order) ~depth:3 ~step:"3" ~expected:9;
-    ()
+    ();
+    Lwt.return_unit
 end
 
 let tests =
-  let tc_sync name f = Alcotest.test_case name `Quick f in
-  let tc name f = tc_sync name (fun () -> Lwt_main.run (f ())) in
+  let tc_sync name f = Alcotest_lwt.test_case name `Quick f in
+  let tc name f = tc_sync name (fun _switch -> f) in
   (* Test disabled because it relies on being able to serialise concrete inodes,
      which is not possible following the introduction of structured keys. *)
   let _ = tc "test truncated inodes" test_truncated_inodes in
diff --git a/test/irmin-pack/test_inode.mli b/test/irmin-pack/test_inode.mli
index 2b40d2f891..4acc26805b 100644
--- a/test/irmin-pack/test_inode.mli
+++ b/test/irmin-pack/test_inode.mli
@@ -14,4 +14,4 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  *)
 
-val tests : unit Alcotest.test_case list
+val tests : unit Alcotest_lwt.test_case list
diff --git a/test/irmin-pack/test_pack.ml b/test/irmin-pack/test_pack.ml
index 906c25b13e..228d8be3ef 100644
--- a/test/irmin-pack/test_pack.ml
+++ b/test/irmin-pack/test_pack.ml
@@ -177,8 +177,10 @@ module Dict = struct
 
   let tests =
     [
-      Alcotest.test_case "dict" `Quick test_dict;
-      Alcotest.test_case "RO dict" `Quick test_readonly_dict;
+      Alcotest_lwt.test_case "dict" `Quick (fun _ () ->
+          Lwt.return (test_dict ()));
+      Alcotest_lwt.test_case "RO dict" `Quick (fun _ () ->
+          Lwt.return (test_readonly_dict ()));
     ]
 end
 
@@ -399,17 +401,17 @@ module Pack = struct
 
   let tests =
     [
-      Alcotest.test_case "pack" `Quick (fun () -> Lwt_main.run (test_pack ()));
-      Alcotest.test_case "RO pack" `Quick (fun () ->
-          Lwt_main.run (test_readonly_pack ()));
-      Alcotest.test_case "close" `Quick (fun () ->
-          Lwt_main.run (test_close_pack ()));
-      Alcotest.test_case "close readonly" `Quick (fun () ->
-          Lwt_main.run (test_close_pack_more ()));
-      Alcotest.test_case "readonly reload, index flush" `Quick (fun () ->
-          Lwt_main.run (readonly_reload_index_flush ()));
-      Alcotest.test_case "readonly find, index flush" `Quick (fun () ->
-          Lwt_main.run (readonly_find_index_flush ()));
+      Alcotest_lwt.test_case "pack" `Quick (fun _switch () -> test_pack ());
+      Alcotest_lwt.test_case "RO pack" `Quick (fun _switch () ->
+          test_readonly_pack ());
+      Alcotest_lwt.test_case "close" `Quick (fun _switch () ->
+          test_close_pack ());
+      Alcotest_lwt.test_case "close readonly" `Quick (fun _switch () ->
+          test_close_pack_more ());
+      Alcotest_lwt.test_case "readonly reload, index flush" `Quick
+        (fun _switch () -> readonly_reload_index_flush ());
+      Alcotest_lwt.test_case "readonly find, index flush" `Quick
+        (fun _switch () -> readonly_find_index_flush ());
     ]
 end
 
@@ -487,10 +489,9 @@ module Branch = struct
 
   let tests =
     [
-      Alcotest.test_case "branch" `Quick (fun () ->
-          Lwt_main.run (test_branch ()));
-      Alcotest.test_case "branch close" `Quick (fun () ->
-          Lwt_main.run (test_close_branch ()));
+      Alcotest_lwt.test_case "branch" `Quick (fun _switch -> test_branch);
+      Alcotest_lwt.test_case "branch close" `Quick (fun _switch ->
+          test_close_branch);
     ]
 end
 
diff --git a/test/irmin-pack/test_pack.mli b/test/irmin-pack/test_pack.mli
index e4a19a6027..599c43edf1 100644
--- a/test/irmin-pack/test_pack.mli
+++ b/test/irmin-pack/test_pack.mli
@@ -15,4 +15,4 @@
  *)
 
 val suite : Irmin_test.Suite.t list
-val misc : (string * unit Alcotest.test_case list) list
+val misc : (string * unit Alcotest_lwt.test_case list) list
diff --git a/test/irmin-pack/test_pack_version_bump.ml b/test/irmin-pack/test_pack_version_bump.ml
index 46002f1ab8..17cb1519f5 100644
--- a/test/irmin-pack/test_pack_version_bump.ml
+++ b/test/irmin-pack/test_pack_version_bump.ml
@@ -156,8 +156,8 @@ let test_open_RW () : unit Lwt.t =
   Lwt.return ()
 
 let tests =
-  let f g () = Lwt_main.run @@ g () in
-  Alcotest.
+  let f g _switch () = g () in
+  Alcotest_lwt.
     [
       test_case "test_RO_no_migration" `Quick (f test_RO_no_migration);
       test_case "test_open_RW" `Quick (f test_open_RW);
diff --git a/test/irmin-pack/test_pack_version_bump.mli b/test/irmin-pack/test_pack_version_bump.mli
index d38ba9a90a..01604e1617 100644
--- a/test/irmin-pack/test_pack_version_bump.mli
+++ b/test/irmin-pack/test_pack_version_bump.mli
@@ -1 +1 @@
-val tests : unit Alcotest.test_case list
+val tests : unit Alcotest_lwt.test_case list
diff --git a/test/irmin-pack/test_snapshot.ml b/test/irmin-pack/test_snapshot.ml
index 3be7401fb0..f0cb79b1c6 100644
--- a/test/irmin-pack/test_snapshot.ml
+++ b/test/irmin-pack/test_snapshot.ml
@@ -251,9 +251,7 @@ let test_gced_store_on_disk () =
   S.Repo.close repo_import
 
 let tests =
-  let tc name f =
-    Alcotest.test_case name `Quick (fun () -> Lwt_main.run (f ()))
-  in
+  let tc name f = Alcotest_lwt.test_case name `Quick (fun _switch () -> f ()) in
   [
     tc "in memory minimal" test_in_memory_minimal;
     tc "in memory always" test_in_memory_always;
diff --git a/test/irmin-pack/test_tree.ml b/test/irmin-pack/test_tree.ml
index c03836e70f..42ecbf3d93 100644
--- a/test/irmin-pack/test_tree.ml
+++ b/test/irmin-pack/test_tree.ml
@@ -694,28 +694,28 @@ let test_reexport_node () =
 
 let tests =
   [
-    Alcotest.test_case "fold over keys in sorted order" `Quick (fun () ->
-        Lwt_main.run (test_fold_sorted ()));
-    Alcotest.test_case "fold over keys in random order" `Quick (fun () ->
-        Lwt_main.run (test_fold_random ()));
-    Alcotest.test_case "fold over keys in undefined order" `Quick (fun () ->
-        Lwt_main.run (test_fold_undefined ()));
-    Alcotest.test_case "test Merkle proof for large inodes" `Quick (fun () ->
-        Lwt_main.run (test_large_inode ()));
-    Alcotest.test_case "test Merkle proof for small inodes" `Quick (fun () ->
-        Lwt_main.run (test_small_inode ()));
-    Alcotest.test_case "test deeper Merkle proof" `Quick (fun () ->
-        Lwt_main.run (test_deeper_proof ()));
-    Alcotest.test_case "test large Merkle proof" `Slow (fun () ->
-        Lwt_main.run (test_large_proofs ()));
-    Alcotest.test_case "test extenders in stream proof" `Quick (fun () ->
-        Lwt_main.run (test_extenders ()));
-    Alcotest.test_case "test hardcoded stream proof" `Quick (fun () ->
-        Lwt_main.run (test_hardcoded_stream ()));
-    Alcotest.test_case "test hardcoded proof" `Quick (fun () ->
-        Lwt_main.run (test_hardcoded_proof ()));
-    Alcotest.test_case "test stream proof exn" `Quick (fun () ->
-        Lwt_main.run (test_proof_exn ()));
-    Alcotest.test_case "test reexport node" `Quick (fun () ->
-        Lwt_main.run (test_reexport_node ()));
+    Alcotest_lwt.test_case "fold over keys in sorted order" `Quick
+      (fun _switch -> test_fold_sorted);
+    Alcotest_lwt.test_case "fold over keys in random order" `Quick
+      (fun _switch -> test_fold_random);
+    Alcotest_lwt.test_case "fold over keys in undefined order" `Quick
+      (fun _switch -> test_fold_undefined);
+    Alcotest_lwt.test_case "test Merkle proof for large inodes" `Quick
+      (fun _switch -> test_large_inode);
+    Alcotest_lwt.test_case "test Merkle proof for small inodes" `Quick
+      (fun _switch -> test_small_inode);
+    Alcotest_lwt.test_case "test deeper Merkle proof" `Quick (fun _switch ->
+        test_deeper_proof);
+    Alcotest_lwt.test_case "test large Merkle proof" `Slow (fun _switch ->
+        test_large_proofs);
+    Alcotest_lwt.test_case "test extenders in stream proof" `Quick
+      (fun _switch -> test_extenders);
+    Alcotest_lwt.test_case "test hardcoded stream proof" `Quick (fun _switch ->
+        test_hardcoded_stream);
+    Alcotest_lwt.test_case "test hardcoded proof" `Quick (fun _switch ->
+        test_hardcoded_proof);
+    Alcotest_lwt.test_case "test stream proof exn" `Quick (fun _switch ->
+        test_proof_exn);
+    Alcotest_lwt.test_case "test reexport node" `Quick (fun _switch ->
+        test_reexport_node);
   ]
diff --git a/test/irmin-pack/test_upgrade.ml b/test/irmin-pack/test_upgrade.ml
index 11f3a253b2..4bd42a3406 100644
--- a/test/irmin-pack/test_upgrade.ml
+++ b/test/irmin-pack/test_upgrade.ml
@@ -675,10 +675,10 @@ let test start_mode () =
 (** Product on start_mode *)
 let tests =
   [
-    Alcotest.test_case "upgrade From_v3" `Quick (fun () ->
-        Lwt_main.run (test From_v3 ()));
-    Alcotest.test_case "upgrade From_v2" `Quick (fun () ->
-        Lwt_main.run (test From_v2 ()));
-    Alcotest.test_case "upgrade From_scratch" `Quick (fun () ->
-        Lwt_main.run (test From_scratch ()));
+    Alcotest_lwt.test_case "upgrade From_v3" `Quick (fun _switch () ->
+        test From_v3 ());
+    Alcotest_lwt.test_case "upgrade From_v2" `Quick (fun _switch () ->
+        test From_v2 ());
+    Alcotest_lwt.test_case "upgrade From_scratch" `Quick (fun _switch () ->
+        test From_scratch ());
   ]
diff --git a/test/irmin/dune b/test/irmin/dune
index b1beacea1e..219309ffdf 100644
--- a/test/irmin/dune
+++ b/test/irmin/dune
@@ -11,6 +11,7 @@
   alcotest
   alcotest-lwt
   lwt
+  lwt.unix
   hex
   logs
   logs.fmt))
diff --git a/test/irmin/generic-key/dune b/test/irmin/generic-key/dune
index d1f7df1dad..96e1b41b09 100644
--- a/test/irmin/generic-key/dune
+++ b/test/irmin/generic-key/dune
@@ -4,4 +4,12 @@
  (package irmin-test)
  (preprocess
   (pps ppx_irmin.internal))
- (libraries irmin irmin.mem irmin-test alcotest alcotest-lwt lwt vector))
+ (libraries
+  irmin
+  irmin.mem
+  irmin-test
+  alcotest
+  alcotest-lwt
+  lwt
+  lwt.unix
+  vector))
diff --git a/test/irmin/generic-key/test.ml b/test/irmin/generic-key/test.ml
index b945778c5d..28f52b7cea 100644
--- a/test/irmin/generic-key/test.ml
+++ b/test/irmin/generic-key/test.ml
@@ -15,5 +15,8 @@
  *)
 
 let () =
-  Irmin_test.Store.run __FILE__ ~slow:true ~misc:[]
-    [ (`Quick, Test_store_offset.suite); (`Quick, Test_inlined_contents.suite) ]
+  Lwt_main.run
+  @@ Irmin_test.Store.run __FILE__ ~slow:true ~misc:[] ~sleep:Lwt_unix.sleep
+       [
+         (`Quick, Test_store_offset.suite); (`Quick, Test_inlined_contents.suite);
+       ]