diff --git a/.github/workflows/moocore.yml b/.github/workflows/moocore.yml
index 0387791..f18e657 100644
--- a/.github/workflows/moocore.yml
+++ b/.github/workflows/moocore.yml
@@ -101,3 +101,45 @@ jobs:
           name: failed-tests-${{ matrix.os }}-${{ matrix.cc }}-${{ github.run_id }}
           path: failed-test-outputs/
           if-no-files-found: ignore
+
+  test-windows:
+    if: "! contains(github.event.head_commit.message, '[skip ci]')"
+    name: Run testsuite on windows-latest with MSVC
+    runs-on: windows-latest
+    env:
+      PYTHONUTF8: 1
+    steps:
+      - name: Checkout moocore
+        uses: actions/checkout@v6
+        with:
+          repository: multi-objective/moocore
+          sparse-checkout: c
+
+      - name: Checkout testsuite
+        uses: actions/checkout@v6
+        with:
+          path: testsuite
+
+      - uses: ilammy/msvc-dev-cmd@v1
+
+      - uses: actions/setup-python@v6
+        with:
+          python-version: '3.x'
+
+      - name: Install dependencies
+        run: python -m pip install -r testsuite/requirements.txt
+
+      - name: Build moocore (MSVC)
+        shell: bash
+        run: make -C c all CC=cl DEBUG=1
+
+      - name: Run testsuite
+        # Default shell (PowerShell) on purpose: no Unix tools are required.
+        run: |
+          foreach ($t in "dominatedsets","eaf","epsilon","hv","hvapprox","igd","ndsort","nondominated") {
+            Push-Location "testsuite/$t"
+            python ../regtest.py "$env:GITHUB_WORKSPACE/bin/$t"
+            $rc = $LASTEXITCODE
+            Pop-Location
+            if ($rc -ne 0) { exit $rc }
+          }
diff --git a/README.md b/README.md
index 2e2ab99..7819f31 100644
--- a/README.md
+++ b/README.md
@@ -8,3 +8,38 @@ This is a testsuite for [`moocore`](https://github.com/multi-objective/moocore).
 
 [testsuite-badge]: https://github.com/multi-objective/testsuite/actions/workflows/moocore.yml/badge.svg
 [testsuite-link]: https://github.com/multi-objective/testsuite/actions/workflows/moocore.yml
+
+Running the testsuite
+---------------------
+
+```bash
+pip install -r requirements.txt
+cd hv && ../regtest.py ../../moocore/bin/hv
+```
+
+`regtest.py PROGRAM [TESTS]` runs the `*.test` files in the current directory (recursively) using `PROGRAM`.
+The `*.test` files do not call platform-specific utilities directly but use the environment variables
+`$XZCAT`, `$SORT`, `$CAT_SQUEEZE` and `$MKTEMP`. On Linux/macOS they default to `xzcat`, `sort`, `cat -s` and `mktemp`
+and can be overridden from the environment.
+
+Windows
+-------
+
+The testsuite runs on Windows with the executables of `moocore` built with MSVC.
+`regtest.py` only needs Python and `joblib` (see `requirements.txt`); no Unix utilities are required.
+On Windows, `regtest.py`:
+
+ * runs the `*.test` files with a built-in minimal interpreter (variables, `|`, `<`, `>`, `echo`, `rm`) instead of a shell, and
+ * uses the portable Python scripts in [`tools/`](tools) for `$XZCAT`, `$SORT`, `$CAT_SQUEEZE` and `$MKTEMP`.
+
+moocore's makefile adds the `.exe` extension to the executables, and `regtest.py` appends it if missing, so these are equivalent:
+
+```bat
+rem From a Visual Studio developer prompt (or after ilammy/msvc-dev-cmd)
+make -C moocore\c all CC=cl
+cd testsuite\hv
+python ..\regtest.py ..\..\moocore\bin\hv
+python ..\regtest.py ..\..\moocore\bin\hv.exe
+```
+
+Set `REGTEST_PORTABLE=1` to use this Windows code path on Linux/macOS (useful for debugging).
diff --git a/eaf/eafdiff-ALG_1_dat_ALG_2_dat.test b/eaf/eafdiff-ALG_1_dat_ALG_2_dat.test
index 1d6cb3d..59e4da2 100644
--- a/eaf/eafdiff-ALG_1_dat_ALG_2_dat.test
+++ b/eaf/eafdiff-ALG_1_dat_ALG_2_dat.test
@@ -1,6 +1,6 @@
-file1=$(mktemp)
-file2=$(mktemp)
-xzcat ../data/ALG_1_dat.xz > $file1
-xzcat ../data/ALG_2_dat.xz > $file2
+file1=$($MKTEMP)
+file2=$($MKTEMP)
+${XZCAT} ../data/ALG_1_dat.xz > $file1
+${XZCAT} ../data/ALG_2_dat.xz > $file2
 ${PROGRAM} -d $file1 $file2
 rm -f $file1 $file2
diff --git a/eaf/input1.test b/eaf/input1.test
index bd06482..929ad66 100644
--- a/eaf/input1.test
+++ b/eaf/input1.test
@@ -1 +1 @@
-${PROGRAM} --quiet -i- ../data/input1.dat | sort | cat -s
+${PROGRAM} --quiet -i- ../data/input1.dat | ${SORT} | ${CAT_SQUEEZE}
diff --git a/eaf/ran.1000pts.3d.10.test b/eaf/ran.1000pts.3d.10.test
index a67b5b1..c143427 100644
--- a/eaf/ran.1000pts.3d.10.test
+++ b/eaf/ran.1000pts.3d.10.test
@@ -1 +1 @@
-${PROGRAM} --quiet ../data/ran.1000pts.3d.10 | sort | cat -s
+${PROGRAM} --quiet ../data/ran.1000pts.3d.10 | ${SORT} | ${CAT_SQUEEZE}
diff --git a/eaf/spherical-3d-2000pts-10.test b/eaf/spherical-3d-2000pts-10.test
index 5865316..56076f8 100644
--- a/eaf/spherical-3d-2000pts-10.test
+++ b/eaf/spherical-3d-2000pts-10.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.dat.xz | $PROGRAM --quiet | sort -s | cat -s
+${XZCAT} ../data/${TESTNAME}.dat.xz | $PROGRAM --quiet | ${SORT} -s | ${CAT_SQUEEZE}
diff --git a/epsilon/rmnk_0.0_10_16_1_0_random_search_1.txt.test b/epsilon/rmnk_0.0_10_16_1_0_random_search_1.txt.test
index f12b9a0..744366c 100644
--- a/epsilon/rmnk_0.0_10_16_1_0_random_search_1.txt.test
+++ b/epsilon/rmnk_0.0_10_16_1_0_random_search_1.txt.test
@@ -1,5 +1,5 @@
-reference=$(mktemp)
-xzcat ../data/rmnk_0.0_10_16_1_0_ref.txt.xz > $reference
-xzcat ../data/${TESTNAME}.xz | ${PROGRAM} -r $reference --additive
-xzcat ../data/${TESTNAME}.xz | ${PROGRAM} -r $reference --additive --maximise
+reference=$($MKTEMP)
+${XZCAT} ../data/rmnk_0.0_10_16_1_0_ref.txt.xz > $reference
+${XZCAT} ../data/${TESTNAME}.xz | ${PROGRAM} -r $reference --additive
+${XZCAT} ../data/${TESTNAME}.xz | ${PROGRAM} -r $reference --additive --maximise
 rm -f $reference
diff --git a/hv/ran.40000pts.3d.1.test b/hv/ran.40000pts.3d.1.test
index a7c86c0..bbc7885 100644
--- a/hv/ran.40000pts.3d.1.test
+++ b/hv/ran.40000pts.3d.1.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.xz | ${PROGRAM} -r "10 10 10" --union
+${XZCAT} ../data/${TESTNAME}.xz | ${PROGRAM} -r "10 10 10" --union
diff --git a/hv/ran.40001pts.3d.1.test b/hv/ran.40001pts.3d.1.test
index a7c86c0..bbc7885 100644
--- a/hv/ran.40001pts.3d.1.test
+++ b/hv/ran.40001pts.3d.1.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.xz | ${PROGRAM} -r "10 10 10" --union
+${XZCAT} ../data/${TESTNAME}.xz | ${PROGRAM} -r "10 10 10" --union
diff --git a/hv/rep5d.test b/hv/rep5d.test
index 98e46cb..15c1c3e 100644
--- a/hv/rep5d.test
+++ b/hv/rep5d.test
@@ -1 +1 @@
-xzcat ${TESTNAME}.inp.xz | $PROGRAM -r "-14300 -14300 -14300 -14300 -14300"
+${XZCAT} ${TESTNAME}.inp.xz | $PROGRAM -r "-14300 -14300 -14300 -14300 -14300"
diff --git a/hv/test2D-200k.test b/hv/test2D-200k.test
index 45c25f1..0e47668 100644
--- a/hv/test2D-200k.test
+++ b/hv/test2D-200k.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.inp.xz | $PROGRAM -r "-117751 -117751"
+${XZCAT} ../data/${TESTNAME}.inp.xz | $PROGRAM -r "-117751 -117751"
diff --git a/igd/ALG_1_ALG_2.test b/igd/ALG_1_ALG_2.test
index ba1af0a..438a14f 100644
--- a/igd/ALG_1_ALG_2.test
+++ b/igd/ALG_1_ALG_2.test
@@ -1,7 +1,7 @@
-tmpfile1=$(mktemp -u)
-tmpfile2=$(mktemp -u)
-xzcat ../data/ALG_1_dat.xz > "$tmpfile1"
-xzcat ../data/ALG_2_dat.xz > "$tmpfile2"
+tmpfile1=$($MKTEMP -u)
+tmpfile2=$($MKTEMP -u)
+${XZCAT} ../data/ALG_1_dat.xz > "$tmpfile1"
+${XZCAT} ../data/ALG_2_dat.xz > "$tmpfile2"
 echo "# (1,2)"
 ${PROGRAM} --all -r "$tmpfile1" "$tmpfile2"
 ${PROGRAM} --all --maximise -r "$tmpfile1" "$tmpfile2"
diff --git a/igd/spherical-3d-2000pts-10.test b/igd/spherical-3d-2000pts-10.test
index caeabcd..34e5183 100644
--- a/igd/spherical-3d-2000pts-10.test
+++ b/igd/spherical-3d-2000pts-10.test
@@ -1,4 +1,4 @@
-tmpfile=$(mktemp -u)
-xzcat ../data/${TESTNAME}.dat.xz > "$tmpfile"
+tmpfile=$($MKTEMP -u)
+${XZCAT} ../data/${TESTNAME}.dat.xz > "$tmpfile"
 ${PROGRAM} --all -r "$tmpfile" "$tmpfile"
 rm -f "$tmpfile"
diff --git a/nondominated/DTLZDiscontinuousShape.3d.front.1000pts.10.test b/nondominated/DTLZDiscontinuousShape.3d.front.1000pts.10.test
index 35e48ff..c6e216b 100644
--- a/nondominated/DTLZDiscontinuousShape.3d.front.1000pts.10.test
+++ b/nondominated/DTLZDiscontinuousShape.3d.front.1000pts.10.test
@@ -1 +1 @@
-$PROGRAM < ../data/${TESTNAME} --union --quiet --filter | sort -b
+$PROGRAM < ../data/${TESTNAME} --union --quiet --filter | ${SORT} -b
diff --git a/nondominated/DTLZLinearShape.3d.front.1000pts.10.test b/nondominated/DTLZLinearShape.3d.front.1000pts.10.test
index 35e48ff..c6e216b 100644
--- a/nondominated/DTLZLinearShape.3d.front.1000pts.10.test
+++ b/nondominated/DTLZLinearShape.3d.front.1000pts.10.test
@@ -1 +1 @@
-$PROGRAM < ../data/${TESTNAME} --union --quiet --filter | sort -b
+$PROGRAM < ../data/${TESTNAME} --union --quiet --filter | ${SORT} -b
diff --git a/nondominated/DTLZLinearShape.6d.front.700pts.10.test b/nondominated/DTLZLinearShape.6d.front.700pts.10.test
index 22d5968..af2fc94 100644
--- a/nondominated/DTLZLinearShape.6d.front.700pts.10.test
+++ b/nondominated/DTLZLinearShape.6d.front.700pts.10.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.xz | $PROGRAM  --union --quiet --filter | sort -b
+${XZCAT} ../data/${TESTNAME}.xz | $PROGRAM  --union --quiet --filter | ${SORT} -b
diff --git a/nondominated/DTLZSphereShape.3d.front.1000pts.10.test b/nondominated/DTLZSphereShape.3d.front.1000pts.10.test
index 35e48ff..c6e216b 100644
--- a/nondominated/DTLZSphereShape.3d.front.1000pts.10.test
+++ b/nondominated/DTLZSphereShape.3d.front.1000pts.10.test
@@ -1 +1 @@
-$PROGRAM < ../data/${TESTNAME} --union --quiet --filter | sort -b
+$PROGRAM < ../data/${TESTNAME} --union --quiet --filter | ${SORT} -b
diff --git a/nondominated/DTLZSphereShape.5d.front.1000pts.10.test b/nondominated/DTLZSphereShape.5d.front.1000pts.10.test
index 35e48ff..c6e216b 100644
--- a/nondominated/DTLZSphereShape.5d.front.1000pts.10.test
+++ b/nondominated/DTLZSphereShape.5d.front.1000pts.10.test
@@ -1 +1 @@
-$PROGRAM < ../data/${TESTNAME} --union --quiet --filter | sort -b
+$PROGRAM < ../data/${TESTNAME} --union --quiet --filter | ${SORT} -b
diff --git a/nondominated/DTLZSphereShape.6d.front.1000pts.10.test b/nondominated/DTLZSphereShape.6d.front.1000pts.10.test
index dc423ba..bab99d6 100644
--- a/nondominated/DTLZSphereShape.6d.front.1000pts.10.test
+++ b/nondominated/DTLZSphereShape.6d.front.1000pts.10.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.xz | $PROGRAM --union --quiet --filter | sort -b
+${XZCAT} ../data/${TESTNAME}.xz | $PROGRAM --union --quiet --filter | ${SORT} -b
diff --git a/nondominated/ran.1000pts.3d.10.test b/nondominated/ran.1000pts.3d.10.test
index 321a9ac..2d02fc4 100644
--- a/nondominated/ran.1000pts.3d.10.test
+++ b/nondominated/ran.1000pts.3d.10.test
@@ -1 +1 @@
-xzcat ../eaf/${TESTNAME}.exp.xz | $PROGRAM --union --quiet --filter | sort -b
+${XZCAT} ../eaf/${TESTNAME}.exp.xz | $PROGRAM --union --quiet --filter | ${SORT} -b
diff --git a/nondominated/ran.1300pts.5d.10.test b/nondominated/ran.1300pts.5d.10.test
index d5b92ba..5f8aaa9 100644
--- a/nondominated/ran.1300pts.5d.10.test
+++ b/nondominated/ran.1300pts.5d.10.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.xz | $PROGRAM --maximise --union --quiet --filter | sort -b
+${XZCAT} ../data/${TESTNAME}.xz | $PROGRAM --maximise --union --quiet --filter | ${SORT} -b
diff --git a/nondominated/ran.40000pts.3d.1.test b/nondominated/ran.40000pts.3d.1.test
index 2ce61bf..5ef29e2 100644
--- a/nondominated/ran.40000pts.3d.1.test
+++ b/nondominated/ran.40000pts.3d.1.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.xz | $PROGRAM --verbose
+${XZCAT} ../data/${TESTNAME}.xz | $PROGRAM --verbose
diff --git a/nondominated/ran.9000pts.4d.10.test b/nondominated/ran.9000pts.4d.10.test
index d5b92ba..5f8aaa9 100644
--- a/nondominated/ran.9000pts.4d.10.test
+++ b/nondominated/ran.9000pts.4d.10.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.xz | $PROGRAM --maximise --union --quiet --filter | sort -b
+${XZCAT} ../data/${TESTNAME}.xz | $PROGRAM --maximise --union --quiet --filter | ${SORT} -b
diff --git a/nondominated/rmnk_0.0_10_16_1_0_random_search_1.txt.test b/nondominated/rmnk_0.0_10_16_1_0_random_search_1.txt.test
index 5e7536b..9130259 100644
--- a/nondominated/rmnk_0.0_10_16_1_0_random_search_1.txt.test
+++ b/nondominated/rmnk_0.0_10_16_1_0_random_search_1.txt.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.xz | $PROGRAM --union --verbose
+${XZCAT} ../data/${TESTNAME}.xz | $PROGRAM --union --verbose
diff --git a/nondominated/test2D-200k.test b/nondominated/test2D-200k.test
index 2058d84..2faf410 100644
--- a/nondominated/test2D-200k.test
+++ b/nondominated/test2D-200k.test
@@ -1 +1 @@
-xzcat ../data/${TESTNAME}.inp.xz | $PROGRAM --quiet --filter | sort -b -s
+${XZCAT} ../data/${TESTNAME}.inp.xz | $PROGRAM --quiet --filter | ${SORT} -b -s
diff --git a/regtest.py b/regtest.py
index 5b2bb05..da54ff1 100755
--- a/regtest.py
+++ b/regtest.py
@@ -5,10 +5,13 @@
 import glob
 import time
 import tempfile
+import shlex
 from itertools import zip_longest
-from joblib import Parallel, delayed
+from pathlib import Path
 from rich import print as print_rich
 
+from joblib import Parallel, delayed
+
 import re
 import difflib
 import lzma
@@ -16,6 +19,53 @@
 # debug = True will use the command-line diff (or xzdiff) to check the results of difflib.
 debug = False
 
+IS_WINDOWS = sys.platform == "win32"
+# Set REGTEST_PORTABLE=1 to use the Windows code path on other platforms.
+USE_PORTABLE = IS_WINDOWS or os.getenv("REGTEST_PORTABLE") == "1"
+
+# Make sure that Python subprocesses and joblib workers use UTF-8.
+os.environ.setdefault("PYTHONUTF8", "1")
+os.environ.setdefault("PYTHONIOENCODING", "utf-8")
+
+
+def setup_utf8_output():
+    """Avoid console-encoding crashes when printing unicode symbols."""
+    for stream in (sys.stdout, sys.stderr):
+        if hasattr(stream, "reconfigure"):
+            try:
+                stream.reconfigure(encoding="utf-8", errors="replace")
+            except (OSError, ValueError):
+                pass
+
+
+setup_utf8_output()
+
+TOOLS_DIR = Path(__file__).resolve().parent / "tools"
+
+
+def _python_tool(script):
+    return shlex.join([Path(sys.executable).as_posix(), (TOOLS_DIR / script).as_posix()])
+
+
+# Commands used by the *.test files. Unix defaults are the standard utilities,
+# on Windows they are portable Python scripts from tools/. They can be
+# overridden by setting the corresponding environment variable.
+if USE_PORTABLE:
+    _TOOL_DEFAULTS = {
+        "XZCAT": _python_tool("xzcat.py"),
+        "SORT": _python_tool("sort.py"),
+        "CAT_SQUEEZE": _python_tool("cat_squeeze.py"),
+        "MKTEMP": _python_tool("mktemp.py"),
+    }
+else:
+    _TOOL_DEFAULTS = {
+        "XZCAT": "xzcat",
+        "SORT": "sort",
+        "CAT_SQUEEZE": "cat -s",
+        "MKTEMP": "mktemp",
+    }
+TOOL_ENV = {k: os.environ.get(k, v) for k, v in _TOOL_DEFAULTS.items()}
+
 _RE_COMBINE_WHITESPACE = re.compile(r"\s+")
 
 ASAN_OPTIONS = os.getenv("ASAN_OPTIONS", "")
@@ -112,6 +162,140 @@ def truncate_lines(output: str, max_lines: int) -> str:
     return "\n".join(lines[:max_lines] + ["...truncated"])
 
 
+_RE_VAR = re.compile(r"\$(?:(\w+)|\{(\w+)\})")
+_RE_ASSIGN = re.compile(r"^(\w+)=(.*)$")
+_RE_SUBST = re.compile(r"^\$\((.*)\)$")
+
+
+def _expand(word, variables):
+    return _RE_VAR.sub(lambda m: variables.get(m.group(1) or m.group(2), ""), word)
+
+
+def _split_line(line):
+    lex = shlex.shlex(line, posix=True, punctuation_chars="|<>")
+    lex.whitespace_split = True
+    lex.commenters = ""
+    return list(lex)
+
+
+def _run_pipeline(line, variables, cwd, env):
+    """Run one simple pipeline of a test file (a tiny POSIX shell subset).
+
+    Supports variable expansion, '|', '<', '>', and the builtins echo and rm.
+    Returns the combined stdout/stderr of the pipeline as bytes.
+    """
+    stages = [[]]
+    stdin_file = stdout_file = None
+    tokens = _split_line(line)
+    i = 0
+    while i < len(tokens):
+        tok = tokens[i]
+        if tok == "|":
+            stages.append([])
+        elif tok in ("<", ">"):
+            i += 1
+            target = _expand(tokens[i], variables)
+            if tok == "<":
+                stdin_file = target
+            else:
+                stdout_file = target
+        else:
+            stages[-1].append(tok)
+        i += 1
+
+    argvs = []
+    for words in stages:
+        argv = []
+        for j, w in enumerate(words):
+            expanded = _expand(w, variables)
+            if j == 0 and w.startswith("$") and expanded.strip():
+                argv.extend(shlex.split(expanded))  # command stored in a variable
+            else:
+                argv.append(expanded)
+        argvs.append(argv)
+
+    if len(argvs) == 1 and argvs[0] and argvs[0][0] in ("echo", "rm"):
+        argv = argvs[0]
+        if argv[0] == "echo":
+            out = (" ".join(argv[1:]) + "\n").encode("utf-8")
+            if stdout_file:
+                Path(cwd or ".", stdout_file).write_bytes(out)
+                return b""
+            return out
+        for name in (a for a in argv[1:] if not a.startswith("-")):
+            try:
+                os.remove(os.path.join(cwd or ".", name))
+            except OSError:
+                pass
+        return b""
+
+    opened = []
+    procs = []
+    errs = []
+    try:
+        prev_out = None
+        if stdin_file:
+            prev_out = open(os.path.join(cwd or ".", stdin_file), "rb")
+            opened.append(prev_out)
+        for k, argv in enumerate(argvs):
+            last = k == len(argvs) - 1
+            if last and stdout_file:
+                stdout = open(os.path.join(cwd or ".", stdout_file), "wb")
+                opened.append(stdout)
+            else:
+                stdout = subprocess.PIPE
+            if last:
+                stderr = subprocess.STDOUT
+            else:
+                stderr = tempfile.TemporaryFile()
+                errs.append(stderr)
+            p = subprocess.Popen(
+                argv, stdin=prev_out, stdout=stdout, stderr=stderr, cwd=cwd, env=env
+            )
+            if k > 0:
+                procs[-1].stdout.close()
+            procs.append(p)
+            prev_out = p.stdout
+        out = procs[-1].communicate()[0] or b""
+        for p in procs[:-1]:
+            p.wait()
+        extra = b""
+        for e in errs:
+            e.seek(0)
+            extra += e.read()
+            e.close()
+        return extra + out
+    finally:
+        for f in opened:
+            f.close()
+
+
+def run_script_portable(script, cwd, env):
+    """Execute a *.test file without a POSIX shell (used on Windows)."""
+    variables = {k: env[k] for k in env}
+    output = b""
+    with open(os.path.join(cwd or ".", script), "r", encoding="utf-8") as fh:
+        lines = fh.read().splitlines()
+    for line in lines:
+        line = line.strip()
+        if not line or line.startswith("#"):
+            continue
+        m = _RE_ASSIGN.match(line)
+        if m and " " not in m.group(1):
+            name, value = m.groups()
+            sub = _RE_SUBST.match(value)
+            if sub:
+                value = _run_pipeline(sub.group(1), variables, cwd, env)
+                value = value.decode("utf-8").rstrip("\r\n")
+            else:
+                value = "".join(_split_line(value)) if value else ""
+                value = _expand(value, variables)
+            variables[name] = value
+            continue
+        output += _run_pipeline(line, variables, cwd, env)
+    return output
+
+
 def runcmd(command, cwd=None, env=None, outfile=subprocess.DEVNULL):
     # Merge with os.environ to preserve PATH and other environment variables
     full_env = os.environ.copy()
@@ -120,6 +304,16 @@ def runcmd(command, cwd=None, env=None, outfile=subprocess.DEVNULL):
     full_env["LC_ALL"] = "C"  # To avoid problems with sorting.
     full_env["ASAN_OPTIONS"] = ASAN_OPTIONS
     full_env["UBSAN_OPTIONS"] = UBSAN_OPTIONS
+    full_env.update(TOOL_ENV)
+    full_env["PYTHONUTF8"] = "1"
+    full_env["PYTHONIOENCODING"] = "utf-8"
+    if USE_PORTABLE and command.startswith(". ./"):
+        data = run_script_portable(command[4:], cwd, full_env)
+        if outfile != subprocess.DEVNULL:
+            open_func = lzma.open if outfile.endswith(".xz") else open
+            with open_func(outfile, "wb") as fh:
+                fh.write(data)
+        return 0
     stdout = outfile if outfile == subprocess.DEVNULL else subprocess.PIPE
     result = subprocess.run(
         command,
@@ -139,6 +333,18 @@ def runcmd(command, cwd=None, env=None, outfile=subprocess.DEVNULL):
     return result.returncode
 
 
+def find_exe(fpath):
+    """Return the path of the executable, adding '.exe' on Windows if needed.
+
+    moocore's makefile appends '.exe' to the executables it builds.
+    """
+    fpath = os.path.realpath(os.path.expanduser(fpath))
+    if IS_WINDOWS and not fpath.lower().endswith(".exe"):
+        if os.path.isfile(fpath + ".exe") or not os.path.isfile(fpath):
+            fpath += ".exe"
+    return fpath
+
+
 def is_exe(fpath):
     fpath = os.path.expanduser(fpath)
     return (
@@ -149,6 +355,9 @@ def is_exe(fpath):
 
 
 def run_test(test, program):
+    setup_utf8_output()
+    if USE_PORTABLE:
+        program = Path(program).as_posix()
     print("{:<60}".format("Running " + test + " :"), end=" ")
     testdirname = os.path.dirname(test)
     if testdirname == "":
@@ -194,7 +403,7 @@ def main():
         print("\t for example:", sys.argv[0], "../bin/hv")
         sys.exit(1)
 
-    program = os.path.realpath(os.path.expanduser(sys.argv[1]))
+    program = find_exe(sys.argv[1])
     if not is_exe(program):
         print(f"error: '{program}' not found or not executable!")
         sys.exit(1)
@@ -214,7 +423,13 @@ def main():
 
     ntotal = len(tests)
     elapsed_time = time.time()
-    ok = Parallel(n_jobs=-2)(delayed(run_test)(test, program=program) for test in tests)
+    # The loky backend starts worker processes with spawn semantics on every
+    # platform (as required on Windows), so run_test is a top-level function
+    # and all its arguments are picklable. Workers inherit PYTHONUTF8 and
+    # PYTHONIOENCODING from the environment set at import time.
+    ok = Parallel(n_jobs=-2, backend="loky")(
+        delayed(run_test)(test, program=program) for test in tests
+    )
     elapsed_time = time.time() - elapsed_time
     npassed = sum(ok)
     nfailed = ntotal - npassed
diff --git a/tools/cat_squeeze.py b/tools/cat_squeeze.py
new file mode 100644
index 0000000..a9af2fd
--- /dev/null
+++ b/tools/cat_squeeze.py
@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+"""Portable replacement for ``cat --squeeze-blank`` (``cat -s``)."""
+import sys
+
+
+def main(files):
+    out = sys.stdout.buffer
+    previous_blank = False
+    for name in files or ["-"]:
+        if name == "-":
+            f = sys.stdin.buffer
+        else:
+            f = open(name, "rb")
+        for line in f:
+            blank = line.rstrip(b"\r\n") == b""
+            if blank and previous_blank:
+                continue
+            previous_blank = blank
+            out.write(line)
+        if f is not sys.stdin.buffer:
+            f.close()
+    out.flush()
+
+
+if __name__ == "__main__":
+    main(sys.argv[1:])
diff --git a/tools/mktemp.py b/tools/mktemp.py
new file mode 100644
index 0000000..26b9872
--- /dev/null
+++ b/tools/mktemp.py
@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+"""Portable replacement for ``mktemp [-u]``: print a temporary file name."""
+import os
+import sys
+import tempfile
+from pathlib import Path
+
+
+def main(args):
+    if args and args[0] not in ("-u", "--dry-run"):
+        sys.exit(f"mktemp.py: unsupported option {args[0]}")
+    if args:
+        # Name only: do not create the file.
+        path = Path(tempfile.gettempdir()) / ("tmp." + os.urandom(6).hex())
+    else:
+        fd, name = tempfile.mkstemp()
+        os.close(fd)
+        path = Path(name)
+    print(path.as_posix())
+
+
+if __name__ == "__main__":
+    main(sys.argv[1:])
diff --git a/tools/sort.py b/tools/sort.py
new file mode 100644
index 0000000..470c685
--- /dev/null
+++ b/tools/sort.py
@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+"""Portable replacement for ``sort`` (LC_ALL=C order) supporting
+``-b/--ignore-leading-blanks`` and ``-s/--stable``."""
+import sys
+
+
+def main(args):
+    blanks = stable = False
+    files = []
+    for a in args:
+        if a == "--ignore-leading-blanks":
+            blanks = True
+        elif a == "--stable":
+            stable = True
+        elif a.startswith("-") and not a.startswith("--") and len(a) > 1:
+            for c in a[1:]:
+                if c == "b":
+                    blanks = True
+                elif c == "s":
+                    stable = True
+                else:
+                    sys.exit(f"sort.py: unsupported option -{c}")
+        else:
+            files.append(a)
+
+    data = b""
+    if not files:
+        files = ["-"]
+    for name in files:
+        if name == "-":
+            data += sys.stdin.buffer.read()
+        else:
+            with open(name, "rb") as f:
+                data += f.read()
+
+    lines = data.split(b"\n")
+    if lines and lines[-1] == b"":
+        lines.pop()
+
+    def key(line):
+        k = line.rstrip(b"\r")
+        return k.lstrip(b" \t") if blanks else k
+
+    if stable:
+        lines.sort(key=key)
+    else:
+        # Like GNU sort, fall back to comparing the whole line.
+        lines.sort(key=lambda x: (key(x), x.rstrip(b"\r")))
+    out = sys.stdout.buffer
+    out.write(b"".join(line + b"\n" for line in lines))
+    out.flush()
+
+
+if __name__ == "__main__":
+    main(sys.argv[1:])
diff --git a/tools/xzcat.py b/tools/xzcat.py
new file mode 100644
index 0000000..2d537ec
--- /dev/null
+++ b/tools/xzcat.py
@@ -0,0 +1,22 @@
+#!/usr/bin/env python3
+"""Portable replacement for ``xzcat``: decompress FILEs (or stdin) to stdout."""
+import lzma
+import shutil
+import sys
+
+
+def main(files):
+    out = sys.stdout.buffer
+    if not files:
+        files = ["-"]
+    for name in files:
+        if name == "-":
+            shutil.copyfileobj(lzma.LZMAFile(sys.stdin.buffer), out)
+        else:
+            with lzma.open(name, "rb") as f:
+                shutil.copyfileobj(f, out)
+    out.flush()
+
+
+if __name__ == "__main__":
+    main(sys.argv[1:])