diff --git a/src/client/opamAdminRepoUpgrade.ml b/src/client/opamAdminRepoUpgrade.ml
index 5ce06fafb4d..6f8f774e35c 100644
--- a/src/client/opamAdminRepoUpgrade.ml
+++ b/src/client/opamAdminRepoUpgrade.ml
@@ -372,6 +372,9 @@ let do_upgrade repo_root =
         "CAML_LD_LIBRARY_PATH", PlusEq, "%{lib}%/stublibs", None;
         "OCAML_TOPLEVEL_PATH", Eq, "%{toplevel}%", None;
       ] |>
+      O.with_extensions
+        (OpamStd.String.Map.singleton OpamFile.OPAM.rewrite_xfield
+           (OpamTypesBase.nullify_pos (OpamParserTypes.FullPos.Bool true))) |>
       (* leave the Compiler flag to the implementations (since the user
          needs to select one)
          O.with_flags [Pkgflag_Compiler] |> *)
diff --git a/tests/reftests/admin.test b/tests/reftests/admin.test
index 6cef5b203d9..aeab50a4704 100644
--- a/tests/reftests/admin.test
+++ b/tests/reftests/admin.test
@@ -101,6 +101,7 @@ src: "file://${BASEDIR}/old-comp.1.2.tgz"
 checksum: "md5=HASH
 }
 ### opam-cat packages/ocaml/ocaml.1.2/opam
+available: opam-version >= "2.2"
 build: ["ocaml" "-I" "+unix" "unix.cma" "gen_ocaml_config.ml"]
 build-env: CAML_LD_LIBRARY_PATH = ""
 depends: ["ocaml-base-compiler" {= "1.2"} | "ocaml-variants" {>= "1.2" & < "1.3~"} | "ocaml-system" {= "1.2"}]
@@ -110,6 +111,7 @@ opam-version: "2.0"
 setenv: [[CAML_LD_LIBRARY_PATH = "%{_:stubsdir}%"] [CAML_LD_LIBRARY_PATH += "%{lib}%/stublibs"] [OCAML_TOPLEVEL_PATH = "%{toplevel}%"]]
 substs: "gen_ocaml_config.ml"
 synopsis: "The OCaml compiler (virtual package)"
+x-allow-env-path-rewrite-on-windows: true
 ### cat packages/ocaml/ocaml.1.2/files/gen_ocaml_config.ml.in
 let () =
   let ocaml_version =