diff --git a/.github/workflows/ci-tests.yml b/.github/workflows/ci-tests.yml
index e331e72d..d42e2c8b 100644
--- a/.github/workflows/ci-tests.yml
+++ b/.github/workflows/ci-tests.yml
@@ -20,7 +20,7 @@ jobs:
     strategy:
       matrix:
         py-ver-major: [3]
-        py-ver-minor: [8, 9, 10, 11, 12]
+        py-ver-minor: [8, 9, 10, 11, 12, 13]
         step: [lint, unit, bandit, mypy]
 
     env:
diff --git a/cwl_utils/__meta__.py b/cwl_utils/__meta__.py
index 088ff715..32c28088 100644
--- a/cwl_utils/__meta__.py
+++ b/cwl_utils/__meta__.py
@@ -1,3 +1,3 @@
 # SPDX-License-Identifier: Apache-2.0
 """Global version number for the cwl_utils package."""
-__version__ = "0.33"
+__version__ = "0.34"
diff --git a/pyproject.toml b/pyproject.toml
index 7d2e1f16..01ba0a89 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,7 +29,7 @@ classifiers = [
     "Topic :: System :: Distributed Computing",
     "Typing :: Typed",
 ]
-requires-python = ">=3.8"
+requires-python = ">=3.8,<3.14"
 dynamic = ["version", "dependencies"]
 
 [project.urls]
diff --git a/tests/test_etools_to_clt.py b/tests/test_etools_to_clt.py
index bf5eb84c..378b281c 100644
--- a/tests/test_etools_to_clt.py
+++ b/tests/test_etools_to_clt.py
@@ -2,9 +2,10 @@
 """Test the CWL Expression refactoring tool."""
 import os
 import shutil
+import sys
 import tarfile
 from pathlib import Path
-from typing import Generator
+from typing import TYPE_CHECKING, Generator, cast
 
 import pytest
 import requests
@@ -22,6 +23,9 @@
 
 from .util import get_data
 
+if TYPE_CHECKING:
+    from http.client import HTTPResponse
+
 
 def test_v1_0_workflow_top_level_format_expr() -> None:
     """Test for the correct error when converting a format expression in a workflow level input."""
@@ -244,11 +248,17 @@ def cwl_v1_0_dir(
 ) -> Generator[str, None, None]:
     """Download the CWL 1.0.2 specs and return a path to the directory."""
     tmp_path = tmp_path_factory.mktemp("cwl_v1_0_dir")
-    with requests.get(
-        "https://github.com/common-workflow-language/common-workflow-language/archive/v1.0.2.tar.gz",
-        stream=True,
-    ).raw as specfileobj:
+    with cast(
+        "HTTPResponse",
+        requests.get(
+            "https://github.com/common-workflow-language/common-workflow-language/archive/v1.0.2.tar.gz",
+            stream=True,
+        ).raw,
+    ) as specfileobj:
         tf = tarfile.open(fileobj=specfileobj)
-        tf.extractall(path=tmp_path)
+        if sys.version_info > (3, 12):
+            tf.extractall(path=tmp_path, filter="data")
+        else:
+            tf.extractall(path=tmp_path)
     yield str(tmp_path / "common-workflow-language-1.0.2")
     shutil.rmtree(os.path.join(tmp_path))
diff --git a/tests/test_examples.py b/tests/test_examples.py
index 4027f7e1..db2fe7c2 100644
--- a/tests/test_examples.py
+++ b/tests/test_examples.py
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 """Tests of example Python scripts."""
 import os
+import runpy
 from pathlib import Path
 
 
@@ -9,11 +10,7 @@ def test_load_example() -> None:
     cwd = Path.cwd()
     parent = Path(__file__).resolve().parent
     os.chdir(parent.parent)
-    exec(
-        open(parent / "load_cwl_by_path.py").read(),
-        globals(),
-        locals(),
-    )
+    result_raw = runpy.run_path(str(parent / "load_cwl_by_path.py"))
     os.chdir(cwd)
-    result = locals()["saved_obj"]
+    result = result_raw["saved_obj"]
     assert result["class"] == "Workflow"
diff --git a/tox.ini b/tox.ini
index 651ba372..7f862333 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,9 +1,9 @@
 [tox]
 envlist =
-  py3{8,9,10,11,12}-lint,
-  py3{8,9,10,11,12}-unit,
-  py3{8,9,10,11,12}-bandit,
-  py3{8,9,10,11,12}-mypy,
+  py3{8,9,10,11,12,13}-lint,
+  py3{8,9,10,11,12,13}-unit,
+  py3{8,9,10,11,12,13}-bandit,
+  py3{8,9,10,11,12,13}-mypy,
   py312-lint-readme,
   py312-pydocstyle
 isolated_build = True
@@ -19,13 +19,14 @@ python =
   3.10: py310
   3.11: py311
   3.12: py312
+  3.13: py313
 
 [testenv]
 description =
-  py3{8,9,10,11,12}-unit: Run the unit tests
-  py3{8,9,10,11,12}-lint: Lint the Python code
-  py3{8,9,10,11,12}-bandit: Search for common security issues
-  py3{8,9,10,11,12}-mypy: Check for type safety
+  py3{8,9,10,11,12,13}-unit: Run the unit tests
+  py3{8,9,10,11,12,13}-lint: Lint the Python code
+  py3{8,9,10,11,12,13}-bandit: Search for common security issues
+  py3{8,9,10,11,12,13}-mypy: Check for type safety
   py312-pydocstyle: docstring style checker
   py312-lint-readme: Lint the README.rst->.md conversion
 
@@ -33,34 +34,34 @@ passenv =
   CI
   GITHUB_*
 deps =
-  py3{8,9,10,11,12}-{unit,mypy}: -rrequirements.txt
-  py3{8,9,10,11,12}-{unit,mypy}: -rtest-requirements.txt
-  py3{8,9,10,11,12}-lint: -rlint-requirements.txt
-  py3{8,9,10,11,12}-bandit: bandit
-  py3{8,9,10,11,12}-mypy: -rmypy-requirements.txt
+  py3{8,9,10,11,12,13}-{unit,mypy}: -rrequirements.txt
+  py3{8,9,10,11,12,13}-{unit,mypy}: -rtest-requirements.txt
+  py3{8,9,10,11,12,13}-lint: -rlint-requirements.txt
+  py3{8,9,10,11,12,13}-bandit: bandit
+  py3{8,9,10,11,12,13}-mypy: -rmypy-requirements.txt
 
 setenv =
-  py3{8,9,10,11,12}-unit: LC_ALL = C.UTF-8
+  py3{8,9,10,11,12,13}-unit: LC_ALL = C.UTF-8
 
 commands =
-  py3{8,9,10,11,12}-unit: python -m pip install -U pip setuptools wheel
-  py3{8,9,10,11,12}-unit: make coverage-report coverage.xml PYTEST_EXTRA={posargs}
-  py3{8,9,10,11,12}-bandit: bandit --recursive cwl_utils
-  py3{8,9,10,11,12}-lint: make flake8
-  py3{8,9,10,11,12}-lint: make format-check
-  py3{8,9,10,11,12}-mypy: make mypy
+  py3{8,9,10,11,12,13}-unit: python -m pip install -U pip setuptools wheel
+  py3{8,9,10,11,12,13}-unit: make coverage-report coverage.xml PYTEST_EXTRA={posargs}
+  py3{8,9,10,11,12,13}-bandit: bandit --recursive cwl_utils
+  py3{8,9,10,11,12,13}-lint: make flake8
+  py3{8,9,10,11,12,13}-lint: make format-check
+  py3{8,9,10,11,12,13}-mypy: make mypy
 
 allowlist_externals =
-  py3{8,9,10,11,12}-lint: flake8
-  py3{8,9,10,11,12}-lint: black
-  py3{8,9,10,11,12}-{mypy,shellcheck,lint,unit}: make
+  py3{8,9,10,11,12,13}-lint: flake8
+  py3{8,9,10,11,12,13}-lint: black
+  py3{8,9,10,11,12,13}-{mypy,shellcheck,lint,unit}: make
 
 skip_install =
-  py3{8,9,10,11,12}-lint: true
-  py3{8,9,10,11,12}-bandit: true
+  py3{8,9,10,11,12,13}-lint: true
+  py3{8,9,10,11,12,13}-bandit: true
 
 extras =
-  py3{8,9,10,11,12}-unit: pretty
+  py3{8,9,10,11,12,13}-unit: pretty
 
 [testenv:py312-pydocstyle]
 allowlist_externals = make