This fixes the following errors:
Error: The module Time_unix.Span is an alias for module Time_float_unix.Span, which is missing
Error: Unbound module Time_float_unix
---
diff --git a/src/alcotest-async/alcotest_async.ml b/src/alcotest-async/alcotest_async.ml
index 97ed610..b6a826f 100644
--- a/src/alcotest-async/alcotest_async.ml
+++ b/src/alcotest-async/alcotest_async.ml
@@ -7,7 +7,7 @@ let run_test timeout name fn args =
   | `Timeout ->
       Alcotest.fail
         (Printf.sprintf "%s timed out after %s" name
-           (Time_unix.Span.to_string_hum timeout))
+           (Time_float_unix.Span.to_string_hum timeout))
 
 module Promise = struct
   include Deferred
@@ -24,7 +24,7 @@ module V1 = struct
 
   let test_case_sync n s f = test_case n s (fun x -> Deferred.return (f x))
 
-  let test_case ?(timeout = Time_unix.Span.of_sec 2.) name s f =
+  let test_case ?(timeout = Time_float_unix.Span.of_sec 2.) name s f =
     test_case name s (run_test timeout name f)
 end
 
diff --git a/src/alcotest-async/alcotest_async_intf.ml b/src/alcotest-async/alcotest_async_intf.ml
index 27df58c..baa55cd 100644
--- a/src/alcotest-async/alcotest_async_intf.ml
+++ b/src/alcotest-async/alcotest_async_intf.ml
@@ -2,7 +2,7 @@ module type V1 = sig
   include Alcotest_engine.V1.Cli.S with type return = unit Async.Deferred.t
 
   val test_case :
-    ?timeout:Time_unix.Span.t ->
+    ?timeout:Time_float_unix.Span.t ->
     string ->
     Alcotest.speed_level ->
     ('a -> unit Async.Deferred.t) ->
diff --git a/src/alcotest-async/dune b/src/alcotest-async/dune
index 9497c26..52ab50c 100644
--- a/src/alcotest-async/dune
+++ b/src/alcotest-async/dune
@@ -9,4 +9,4 @@
   async_unix
   base
   core
-  core_unix.time_unix))
+  core_unix.time_float_unix))