diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a8d312d..0db2bbc 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -196,6 +196,11 @@ jobs:
           # packaging needed by glib
           python3 -m pip install --break-system-packages license-expression \
               packaging
+      - name: Install Python (macOS)
+        if: matrix.os == 'macos'
+        uses: actions/setup-python@v6
+        with:
+          python-version: '3.14'
       - name: Download source tarball
         uses: actions/download-artifact@v6
         with:
diff --git a/artifacts/python/README.md b/artifacts/python/README.md
index 026f9e2..f5b9b53 100644
--- a/artifacts/python/README.md
+++ b/artifacts/python/README.md
@@ -20,17 +20,13 @@ of OpenSlide.
 Install with `pip install openslide-bin`.  OpenSlide Python ≥ 1.4.0 will
 automatically find openslide-bin and use it.
 
-openslide-bin is available for Python 3.9+ on the following platforms:
+openslide-bin is available for Python 3.10+ on the following platforms:
 
 - Linux aarch64 and x86_64 with glibc 2.28+ (Debian, Fedora, RHEL 8+,
   Ubuntu, many others)
 - macOS 11+ (arm64 and x86_64)
 - Windows 10+ and Windows Server 2016+ (x64)
 
-pip older than 20.3 cannot install openslide-bin, claiming that it `is not a
-supported wheel on this platform`.  On platforms with these versions of pip
-(RHEL 8), upgrade pip first with `pip install --upgrade pip`.
-
 ## Using
 
 Use OpenSlide via [OpenSlide Python][].  The OpenSlide Python
diff --git a/artifacts/python/pyproject.in.toml b/artifacts/python/pyproject.in.toml
index 3eb2e0f..14a4116 100644
--- a/artifacts/python/pyproject.in.toml
+++ b/artifacts/python/pyproject.in.toml
@@ -19,7 +19,6 @@ classifiers = [
     "Operating System :: POSIX :: Linux",
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
@@ -28,7 +27,7 @@ classifiers = [
     "Topic :: Scientific/Engineering :: Bio-Informatics",
     "Typing :: Typed",
 ]
-requires-python = ">= 3.9"
+requires-python = ">= 3.10"
 
 [project.urls]
 Homepage = "https://openslide.org/"
diff --git a/bintool b/bintool
index 4590c1f..5b9e3fd 100755
--- a/bintool
+++ b/bintool
@@ -35,6 +35,7 @@ import platform
 import shutil
 import subprocess
 import sys
+import sysconfig
 import tarfile
 from tempfile import TemporaryDirectory
 from typing import Any, BinaryIO, Self
@@ -534,14 +535,17 @@ class WheelSmokeTester(SmokeTester):
 
     def _unpack(self, dir: Path) -> None:
         log('Creating virtualenv')
-        # /usr/bin/python3 on macOS because sys.executable may not be a
-        # universal binary
-        python = (
-            '/usr/bin/python3' if self._system == 'macos' else sys.executable
-        )
+        if (
+            self._system == 'macos'
+            and '-universal2' not in sysconfig.get_platform()
+        ):
+            raise Exception(
+                'Testing macOS wheels requires bintool to be run with a '
+                'Python built as a universal binary'
+            )
         # resolve 8.3 shortname of tempdir to avoid venv warning on Windows
         # https://github.com/python/cpython/issues/90329
-        subprocess.check_call([python, '-m', 'venv', dir.resolve()])
+        subprocess.check_call([sys.executable, '-m', 'venv', dir.resolve()])
         if self._update_pip:
             subprocess.check_call(
                 [