diff --git a/ocaml/libs/vhd/vhd_format_lwt_test/parse_test.ml b/ocaml/libs/vhd/vhd_format_lwt_test/parse_test.ml
index 2df99af8ecf..ee68ad8a3ee 100644
--- a/ocaml/libs/vhd/vhd_format_lwt_test/parse_test.ml
+++ b/ocaml/libs/vhd/vhd_format_lwt_test/parse_test.ml
@@ -29,7 +29,7 @@ let diff () =
   let _ = Diff_vhd.disk in
   ()
 
-let tmp_file_dir = "/tmp"
+let tmp_file_dir = Filename.get_temp_dir_name ()
 
 let disk_name_stem = tmp_file_dir ^ "/parse_test."
 
diff --git a/ocaml/libs/vhd/vhd_format_lwt_test/patterns_lwt.ml b/ocaml/libs/vhd/vhd_format_lwt_test/patterns_lwt.ml
index 914bcfb2233..beb1482c3ab 100644
--- a/ocaml/libs/vhd/vhd_format_lwt_test/patterns_lwt.ml
+++ b/ocaml/libs/vhd/vhd_format_lwt_test/patterns_lwt.ml
@@ -29,7 +29,7 @@ module Memory = struct
       Cstruct.sub pages 0 bytes
 end
 
-let disk_name_stem = "/tmp/dynamic."
+let disk_name_stem = Filename.get_temp_dir_name () ^ "/dynamic."
 
 let disk_suffix = ".vhd"