diff --git a/.travis.yml b/.travis.yml
index dfff502..ada9400 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -69,7 +69,7 @@ install:
         pypy3/bin/pypy3 get-pip.py;
         ;;
     esac
-  - PATH=$(pwd -P)/pypy3/bin:$PATH python -m pip install coveralls virtualenv "tox<3"
+  - PATH=$(pwd -P)/pypy3/bin:$PATH python -m pip install coveralls virtualenv "tox ~= 4.9"
 
 script:
   - PATH=$(pwd -P)/pypy3/bin:$PATH tox -v
diff --git a/appveyor.yml b/appveyor.yml
index 4e72861..8a36738 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -52,7 +52,7 @@ install:
   - 'set PATH=%PYTHON_APPDATA_DIR%\Scripts;%PYTHON%\Scripts;%PYTHON%;%PATH%'
   - 'python -m pip install --user -U pip setuptools'
   - 'pip install --user virtualenv'
-  - 'pip install --user "tox<3"'
+  - 'pip install --user "tox~=4.9"'
   - 'pip install --user coveralls'
   # We need wheel installed to build wheels
   - 'pip install --user wheel'
@@ -61,7 +61,7 @@ build_script:
   - 'call'  # Do nothing.
 
 test_script:
-  - 'build.cmd tox -e %TOX_ENV%-without_coverage-appveyor -v'
+  - 'build.cmd tox run -e %TOX_ENV%-without_coverage --discover %PYTHON% -v'
 
 after_test:
   - 'build.cmd python setup.py bdist_wheel'
diff --git a/requirements_dev.txt b/requirements_dev.txt
index 6471fe4..be580b6 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -2,4 +2,4 @@ bump2version
 cython
 sphinx
 virtualenv
-tox<3
+tox ~= 4.9
diff --git a/tox.ini b/tox.ini
index 6b7ea94..c5e5866 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = {py27,py35,py36,py37,py38,py39,py310,pypy,pypy3}-{with,without}_coverage-{,appveyor}
+envlist = {py27,py35,py36,py37,py38,py39,py310,pypy,pypy3}-{with,without}_coverage
 
 [testenv]
 install_command =
@@ -17,7 +17,7 @@ deps =
     {py27,pypy}: mock==1.3.0
     {py27,py35}: biopython<=1.76
     {py36,py37,py38,py39,py310,py311,pypy3}: biopython
-whitelist_externals =
+allowlist_externals =
     mv
 commands =
     ; Notes:
@@ -47,4 +47,3 @@ basepython =
     py310: python3.10
     pypy: pypy
     pypy3: pypy3
-    appveyor: {env:PYTHON:}\\python.exe