diff --git a/tests/reftests/env-dra27.win32.test b/tests/reftests/env-dra27.win32.test
index 2855c188d5d..4c01566de40 100644
--- a/tests/reftests/env-dra27.win32.test
+++ b/tests/reftests/env-dra27.win32.test
@@ -70,5 +70,5 @@ CI	=	/home/ci/config	norewrite	Updated\ by\ package\ setenv-dra27
 FOO	=	this\ does\ not\ require/allow\ a\ rewrite\ entry	;	target	Updated\ by\ package\ setenv-dra27
 MANPATH	=:	${BASEDIR}/OPAM/rewriting/man	Current\ opam\ switch\ man\ dir
 PATH	=+=	${BASEDIR}/OPAM/rewriting/bin	Binary\ dir\ for\ opam\ switch\ rewriting
-### opam env | grep PKG_CONFIG | '/tmp/build_[^/]*/opam-reftest-[^/]*/' -> '${BASEDIR}/'
+### opam env | grep PKG_CONFIG
 PKG_CONFIG_PATH='/cygdrive/c/Program Files/Microsoft Visual Studio/2022/Preview/VC/Tools/MSVC/14.38.33030/bin/HostX64/x64;C:/Program Files/Microsoft Visual Studio/2022/Preview/Common7/IDE/VC/VCPackages;C:/Program Files/Microsoft Visual Studio/2022/Preview/Common7/Tools/:/cygdrive/c/Program Files/Microsoft Visual Studio/2022/Preview/Common7/Tools/:/cygdrive/c/Program Files/Microsoft Visual Studio/2022/Preview/Common7/IDE/VC/VCPackages:/cygdrive/c/Program Files/Microsoft Visual Studio/2022/Preview/VC/Tools/MSVC/14.38.33030/bin/HostX64/x64:${BASEDIR}/OPAM/rewriting/lib/pkgconfig'; export PKG_CONFIG_PATH;
diff --git a/tests/reftests/run.ml b/tests/reftests/run.ml
index 89f70ded413..06ddcb87ca8 100644
--- a/tests/reftests/run.ml
+++ b/tests/reftests/run.ml
@@ -541,6 +541,11 @@ let parse_command = Parse.command
 let common_filters ?opam dir =
    let tmpdir = OpamSystem.real_path (Filename.get_temp_dir_name ()) in
    let open Re in
+   let dir_to_regex dir =
+     if Sys.win32 then
+       [str dir; str (OpamSystem.back_to_forward dir); str (OpamSystem.apply_cygpath dir)]
+     else
+       [str dir] in
    [
      seq [ bol;
            alt [ str "#=== ERROR";
@@ -554,11 +559,10 @@ let common_filters ?opam dir =
      GrepV;
      seq [bol; str cmd_prompt],
      Sed "##% ";
-     alt [str dir; str (OpamSystem.back_to_forward dir)],
+     alt (dir_to_regex dir),
      Sed "${BASEDIR}";
      seq [
-          alt [str tmpdir;
-               str (OpamSystem.back_to_forward tmpdir)];
+          alt (dir_to_regex tmpdir);
           rep (set "/\\");
           str "opam-";
           rep1 (alt [xdigit; char '-'])],