diff --git a/scripts/ensure_min_python_is_tested.py b/scripts/ensure_min_python_is_tested.py
index 279e839b8..67f5bb312 100644
--- a/scripts/ensure_min_python_is_tested.py
+++ b/scripts/ensure_min_python_is_tested.py
@@ -1,6 +1,8 @@
-#!/usr/bin/env python
-# requires that a YAML implementation is available in order to extract github
-# workflows data
+# this script can only be called via
+#    tox -e check-min-python-is-tested
+#
+# no other usages are supported
+import os
 import pathlib
 import subprocess
 import sys
@@ -17,8 +19,18 @@
 YAML = ruamel.yaml.YAML(typ="safe")
 REPO_ROOT = pathlib.Path(__file__).parent.parent
 
+try:
+    VENV_CACHE_DIR = os.environ["VENV_CACHE_DIR"]
+except KeyError:
+    raise RuntimeError(
+        "Cannot run ensure_min_python_is_tested.py without explicitly "
+        "setting VENV_CACHE dir. "
+        "Please ensure that you are invoking it with "
+        "'tox r -e check-min-python-is-tested'."
+    )
+
 proc = subprocess.run(
-    ["python", "scripts/get_python_requires.py"],
+    ["python", "scripts/get_python_requires.py", "--venv-cache-dir", VENV_CACHE_DIR],
     check=True,
     capture_output=True,
     cwd=REPO_ROOT,
diff --git a/scripts/get_python_requires.py b/scripts/get_python_requires.py
index df9709387..bdb615557 100644
--- a/scripts/get_python_requires.py
+++ b/scripts/get_python_requires.py
@@ -33,19 +33,26 @@
     help="How to output the python_requires data. "
     "The default ('lower-bound') mode will print only the lower bound version number.",
 )
+parser.add_argument(
+    "--venv-cache-dir",
+    default=None,
+    help="A directory in which the 'build' virtualenv will be kept for reuse.",
+)
 args = parser.parse_args()
 
-if platform.system() == "Windows":
-    win_cache_dir = os.getenv("LOCALAPPDATA", os.getenv("APPDATA"))
-    assert win_cache_dir, "cannot find APPDATA dir, cannot cache, abort!"
-    cache_dir = pathlib.Path(win_cache_dir)
+if args.venv_cache_dir:
+    VENV_CACHE_DIR = pathlib.Path(args.venv_cache_dir)
 else:
-    cache_dir = pathlib.Path.home() / ".cache"
-
-VENV_CACHE_DIR = cache_dir / "get_python_requires"
+    if platform.system() == "Windows":
+        win_cache_dir = os.getenv("LOCALAPPDATA", os.getenv("APPDATA"))
+        assert win_cache_dir, "cannot find APPDATA dir, cannot cache, abort!"
+        cache_dir = pathlib.Path(win_cache_dir)
+    else:
+        cache_dir = pathlib.Path.home() / ".cache"
+    VENV_CACHE_DIR = cache_dir / "get_python_requires"
 VENV_CACHE_DIR.mkdir(exist_ok=True)
 
-BUILD_VENV = VENV_CACHE_DIR / "venv-build"
+BUILD_VENV = VENV_CACHE_DIR / "get-python-requires-build"
 BUILD_PYTHON = str(BUILD_VENV / "bin" / "python")
 if BUILD_VENV.exists():
     if args.verbose:
diff --git a/tox.ini b/tox.ini
index a534188e3..6502782d9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -105,6 +105,8 @@ description = Check the Requires-Python metadata against CI config
 skip_install = true
 deps = ruamel.yaml<0.18
 commands = python scripts/ensure_min_python_is_tested.py
+setenv =
+    VENV_CACHE_DIR={envdir}
 
 [testenv:prepare-release]
 skip_install = true