diff --git a/ocaml/xe-cli/newcli.ml b/ocaml/xe-cli/newcli.ml
index 04d4faa2921..0e75dbbc877 100644
--- a/ocaml/xe-cli/newcli.ml
+++ b/ocaml/xe-cli/newcli.ml
@@ -633,7 +633,7 @@ let main_loop ifd ofd permitted_filenames =
           with
           | Unix.Unix_error (_, _, _)
             when !delay <= long_connection_retry_timeout ->
-              Thread.delay !delay ;
+              Unix.sleepf !delay ;
               delay := !delay *. 2. ;
               keep_connection ()
           | e ->
diff --git a/ocaml/xenopsd/cli/xn.ml b/ocaml/xenopsd/cli/xn.ml
index 177d9dadd36..74ade92f21e 100644
--- a/ocaml/xenopsd/cli/xn.ml
+++ b/ocaml/xenopsd/cli/xn.ml
@@ -1047,7 +1047,7 @@ let raw_console_proxy sockaddr =
         (fun () -> Unix.close s)
     with
     | Unix.Unix_error (_, _, _) when !delay <= long_connection_retry_timeout ->
-        Thread.delay !delay ;
+        Unix.sleepf !delay ;
         delay := !delay *. 2. ;
         keep_connection ()
     | e ->
diff --git a/ocaml/xenopsd/xc/memory_breakdown.ml b/ocaml/xenopsd/xc/memory_breakdown.ml
index ef676f7b4d0..f11bc6384e2 100644
--- a/ocaml/xenopsd/xc/memory_breakdown.ml
+++ b/ocaml/xenopsd/xc/memory_breakdown.ml
@@ -246,7 +246,7 @@ let print_memory_field_values xc xs =
   flush stdout
 
 (** Sleeps for the given time period in seconds. *)
-let sleep time_period_seconds = Thread.delay time_period_seconds
+let sleep time_period_seconds = Unix.sleepf time_period_seconds
 
 (** Prints a header line of memory field names, and then periodically prints a
     line of memory field values. *)
diff --git a/ocaml/xenopsd/xc/memory_summary.ml b/ocaml/xenopsd/xc/memory_summary.ml
index ff2560f8154..c63e495ccb4 100644
--- a/ocaml/xenopsd/xc/memory_summary.ml
+++ b/ocaml/xenopsd/xc/memory_summary.ml
@@ -36,7 +36,7 @@ let _ =
   let finished = ref false in
   while not !finished do
     finished := !delay < 0. ;
-    if !delay > 0. then Thread.delay !delay ;
+    if !delay > 0. then Unix.sleepf !delay ;
     flush stdout ;
     let physinfo = Xenctrl.physinfo xc in
     let one_page = 4096L in