diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index a3ac27837..5f776d440 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -36,7 +36,7 @@ jobs:
       env:
         PYTHONDEVMODE: "1"  # -X dev
         PYTHONWARNDEFAULTENCODING: "1"  # -X warn_default_encoding
-        PYTHONWARNINGS: "always"  #  -W always
+        PYTHONWARNINGS: "error,always:unclosed:ResourceWarning"
         PYTEST_ADDOPTS: "--cov ./ --cov-append --cov-config pyproject.toml"
         VIRTUALENV_SYSTEM_SITE_PACKAGES: "1"
 
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index a299029c9..ec7730c1f 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -13,7 +13,7 @@ env:
   FORCE_COLOR: "1"
   PYTHONDEVMODE: "1"  # -X dev
   PYTHONWARNDEFAULTENCODING: "1"  # -X warn_default_encoding
-  PYTHONWARNINGS: "always"  #  -W always
+  PYTHONWARNINGS: "error,always:unclosed:ResourceWarning"
 
 jobs:
   ubuntu:
@@ -44,6 +44,8 @@ jobs:
       if: "endsWith(matrix.python, '-dev')"
       with:
         python-version: ${{ matrix.python }}
+      env:
+        PYTHONWARNINGS: ""
     - name: Check Python version
       run: python --version
     - name: Install graphviz
@@ -52,6 +54,8 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         python -m pip install .[test]
+      env:
+        PYTHONWARNINGS: ""
     - name: Install Docutils ${{ matrix.docutils }}
       run: python -m pip install --upgrade "docutils==${{ matrix.docutils }}.*"
     - name: Test with pytest
@@ -71,6 +75,8 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         python -m pip install .[test]
+      env:
+        PYTHONWARNINGS: ""
     - name: Test with pytest
       run: python -m pytest -vv --durations 25
 
@@ -92,7 +98,11 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         python -m pip install .[test]
+      env:
+        PYTHONWARNINGS: ""
     - name: Install Docutils' HEAD
       run: python -m pip install git+https://repo.or.cz/docutils.git\#subdirectory=docutils
+      env:
+        PYTHONWARNINGS: ""
     - name: Test with pytest
       run: python -m pytest -vv
diff --git a/doc/internals/contributing.rst b/doc/internals/contributing.rst
index a8753dddc..195f6a56c 100644
--- a/doc/internals/contributing.rst
+++ b/doc/internals/contributing.rst
@@ -181,7 +181,7 @@ of targets and allows testing against multiple different Python environments:
 * To run unit tests for a specific Python version and turn on deprecation
   warnings so they're shown in the test output::
 
-      PYTHONWARNINGS=all tox -e py310
+      PYTHONWARNINGS=error tox -e py310
 
 * Arguments to ``pytest`` can be passed via ``tox``, e.g., in order to run a
   particular test::
diff --git a/tests/test_ext_napoleon_iterators.py b/tests/test_ext_napoleon_iterators.py
index 7ecdb138d..a8357e4c6 100644
--- a/tests/test_ext_napoleon_iterators.py
+++ b/tests/test_ext_napoleon_iterators.py
@@ -3,8 +3,13 @@
 import sys
 from unittest import TestCase
 
+import pytest
+
 from sphinx.deprecation import RemovedInSphinx70Warning
-from sphinx.ext.napoleon.iterators import modify_iter, peek_iter
+
+with pytest.warns(DeprecationWarning,
+                  match="sphinx.ext.napoleon.iterators is deprecated."):
+    from sphinx.ext.napoleon.iterators import modify_iter, peek_iter
 
 
 class ModuleIsDeprecatedTest(TestCase):
diff --git a/tests/test_setup_command.py b/tests/test_setup_command.py
index ef364676c..510515125 100644
--- a/tests/test_setup_command.py
+++ b/tests/test_setup_command.py
@@ -33,7 +33,7 @@ def setup_command(request, tempdir, rootdir):
 
         proc = subprocess.Popen(
             command,
-            env=dict(os.environ, PYTHONPATH=pythonpath),
+            env=dict(os.environ, PYTHONPATH=pythonpath, PYTHONWARNINGS='default'),
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE)
         yield namedtuple('setup', 'pkgroot,proc')(pkgrootdir, proc)
diff --git a/tox.ini b/tox.ini
index 487b07537..512aa5f74 100644
--- a/tox.ini
+++ b/tox.ini
@@ -21,7 +21,7 @@ description =
 extras =
     test
 setenv =
-    PYTHONWARNINGS = all
+    PYTHONWARNINGS = error
     PYTEST_ADDOPTS = {env:PYTEST_ADDOPTS:} --color yes
 commands=
     python -X dev -X warn_default_encoding -m pytest --durations 25 {posargs}