diff --git a/.github/workflows/run-tox.yml b/.github/workflows/run-tox.yml
new file mode 100644
index 0000000..c656039
--- /dev/null
+++ b/.github/workflows/run-tox.yml
@@ -0,0 +1,48 @@
+name: Run all tox jobs using Python3
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  tests:
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Cache APT Packages
+      uses: awalsh128/cache-apt-pkgs-action@latest
+      with:
+        packages: imagemagick
+        version: 1.0
+        execute_install_scripts: true
+    - name: Run tox
+      run: |
+        python -m pip install --upgrade pip setuptools
+        pip install tox-gh-actions
+        tox
+    - name: JUnit Report Action
+      uses: mikepenz/action-junit-report@v4
+      if: always() # always run even if the previous step fails
+      with:
+        report_paths: 'reports/pytest-*.xml'
+    - name: Upload test artifacts
+      uses: actions/upload-artifact@v4
+      if: always()
+      with:
+        name: tests-${{ matrix.python-version }}
+        retention-days: 4
+        path: |
+          .tox/py*/tmp
+          reports
diff --git a/diff_pdf_visually/diff.py b/diff_pdf_visually/diff.py
index 7d01b69..969c612 100644
--- a/diff_pdf_visually/diff.py
+++ b/diff_pdf_visually/diff.py
@@ -28,7 +28,7 @@ def pdftopng(sourcepath, destdir, basename, verbosity, dpi):
         raise ValueError("destdir not clean: " + repr(destdir))
 
     verbose_run(
-        (verbosity > VERB_PRINT_CMD),
+        (verbosity >= VERB_PRINT_CMD),
         [
             "pdftocairo",
             "-png",
@@ -136,6 +136,17 @@ def pdfdiff_pages(
     assert os.path.isfile(a), "file {} must exist".format(a)
     assert os.path.isfile(b), "file {} must exist".format(b)
 
+    if threshold is None:
+        threshold = DEFAULT_THRESHOLD
+    if verbosity is None:
+        verbosity = DEFAULT_VERBOSITY
+    if dpi is None:
+        dpi = DEFAULT_DPI
+    if num_threads is None:
+        num_threads = DEFAULT_NUM_THREADS
+    if max_report_pagenos is None:
+        max_report_pagenos = MAX_REPORT_PAGENOS
+
     if tempdir == None:
         path_context = tempfile.TemporaryDirectory(prefix="diffpdf-")
     else:
@@ -188,7 +199,7 @@ def pdfdiff_pages(
             diffpath = p / "diff-{}.png".format(pageno)
             logpath = p / "log-{}.txt".format(pageno)
             s = imgdiff(
-                pageapath, pagebpath, diffpath, logpath, (verbosity > VERB_PRINT_CMD)
+                pageapath, pagebpath, diffpath, logpath, (verbosity >= VERB_PRINT_CMD)
             )
             if verbosity >= VERB_PERPAGE:
                 print("- Page {}: significance={}".format(pageno, s))
diff --git a/pyproject.toml b/pyproject.toml
index 9000678..49450cc 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,13 +1,45 @@
 [project]
-name = 'diff-pdf-visually'
-description = 'Quickly check whether there is a visible difference between two PDFs, using ImageMagick and pdftocairo.'
-authors = [{name = 'Bram Geron', email = 'bram@bram.xyz'}]
-license = {text = 'MIT/Apache-2.0'}
+name = "diff-pdf-visually"
+description = "Quickly check whether there is a visible difference between two PDFs, using ImageMagick and pdftocairo."
 readme = "README.rst"
-urls.Homepage = 'https://github.com/bgeron/diff-pdf-visually'
-urls.Source = 'https://github.com/bgeron/diff-pdf-visually'
+authors = [{name = "Bram Geron", email = "bram@bram.xyz"}]
+maintainers = [{name = "Bram Geron", email = "bram@bram.xyz"}]
+license = {text = "MIT/Apache-2.0"}
+classifiers = [
+    'Development Status :: 4 - Beta',
+    'Intended Audience :: Developers',
+    'License :: OSI Approved :: MIT License',
+    'License :: OSI Approved :: Apache Software License',
+    'Natural Language :: English',
+    'Operating System :: OS Independent',
+    'Programming Language :: Python :: 3.6',
+    'Programming Language :: Python :: 3.7',
+    'Programming Language :: Python :: 3.8',
+    'Programming Language :: Python :: 3.9',
+    'Programming Language :: Python :: 3.10',
+    'Programming Language :: Python :: Implementation :: CPython',
+    'Programming Language :: Python :: Implementation :: PyPy',
+]
+dependencies = []
+requires-python = ">=3.6"
 dynamic = ["version"]
 
+[project.optional-dependencies]
+test = [
+    "coverage",
+    "pytest",
+]
+
+[project.urls]
+Homepage = "https://github.com/bgeron/diff-pdf-visually"
+Source = "https://github.com/bgeron/diff-pdf-visually"
+
+[project.scripts]
+diff-pdf-visually = "diff_pdf_visually.__main__:main"
+
+[tool.setuptools.packages.find]
+include = ["diff_pdf_visually*"]
+
 [requires]
 python_version = ['3.6', '3.7', '3.8', '3.9', '3.10']
 
diff --git a/setup.py b/setup.py
index 0376af7..d29f219 100644
--- a/setup.py
+++ b/setup.py
@@ -18,39 +18,8 @@
 with open('README.rst', 'r', encoding='utf-8') as f:
     readme = f.read()
 
-REQUIRES = []
-
 kwargs = {
-    'name': 'diff-pdf-visually',
     'version': version,
-    'description': '',
-    'long_description': readme,
-    'author': 'Bram Geron',
-    'author_email': 'bram@bram.xyz',
-    'maintainer': 'Bram Geron',
-    'maintainer_email': 'bram@bram.xyz',
-    'url': 'https://github.com/bgeron/diff-pdf-visually',
-    'license': 'MIT/Apache-2.0',
-    'classifiers': [
-        'Development Status :: 4 - Beta',
-        'Intended Audience :: Developers',
-        'License :: OSI Approved :: MIT License',
-        'License :: OSI Approved :: Apache Software License',
-        'Natural Language :: English',
-        'Operating System :: OS Independent',
-        'Programming Language :: Python :: 3.6',
-        'Programming Language :: Python :: 3.7',
-        'Programming Language :: Python :: 3.8',
-        'Programming Language :: Python :: 3.9',
-        'Programming Language :: Python :: Implementation :: CPython',
-        'Programming Language :: Python :: Implementation :: PyPy',
-    ],
-    'install_requires': REQUIRES,
-    'tests_require': ['coverage', 'pytest'],
-    'packages': find_packages(exclude=('tests', 'tests.*')),
-    'entry_points': {
-        'console_scripts': ['diff-pdf-visually=diff_pdf_visually.__main__:main'],
-    },
 }
 
 #################### BEGIN USER OVERRIDES ####################
diff --git a/tox.ini b/tox.ini
index cc8c7de..9fde7f3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,14 +1,30 @@
 [tox]
 envlist =
-    py310
+    py{39,310,311,312}
 
 [testenv]
-passenv = *
+extras =
+    test
 deps =
     coverage
     pytest
 commands =
-    python setup.py --quiet clean develop
-    coverage run --parallel-mode -m pytest
+    coverage run --parallel-mode -m pytest {posargs}
     coverage combine --append
     coverage report -m
+
+[testenv:check-packaging]
+skip_install = true
+deps =
+    build
+    twine
+commands =
+    python -m build -o {envtmpdir}/dist
+    twine check {envtmpdir}/dist/*
+
+[gh-actions]
+python =
+  3.9: py39
+  3.10: py310, check-packaging
+  3.11: py311
+  3.12: py312