diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4b31f805b..0a504e9ed 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -61,7 +61,8 @@ jobs:
           - "3.13"
           - "3.14"
           - "3.15"
-          - "pypy3.10"
+          - "pypy3.11"
+          - "pypy3.12"
     env:
       BABEL_CLDR_NO_DOWNLOAD_PROGRESS: "1"
       BABEL_CLDR_QUIET: "1"
diff --git a/conftest.py b/conftest.py
index 015a20440..4ed891ccd 100644
--- a/conftest.py
+++ b/conftest.py
@@ -1,6 +1,9 @@
+import os
 from pathlib import Path
+from unittest import mock
 
-from _pytest.doctest import DoctestModule
+import pytest
+from _pytest.doctest import DoctestItem, DoctestModule
 
 collect_ignore = [
     'babel/messages/setuptools_frontend.py',
@@ -21,3 +24,14 @@ def _is_relative(p1: Path, p2: Path) -> bool:
 def pytest_collect_file(file_path: Path, parent):
     if _is_relative(file_path, babel_path) and file_path.suffix == '.py':
         return DoctestModule.from_parent(parent, path=file_path)
+
+
+@pytest.fixture(autouse=True)
+def _isolate_doctest_environ(request):
+    # Clean up after after doctests that modify environment
+    # variables (e.g. core.default_locale)
+    if isinstance(request.node, DoctestItem):
+        with mock.patch.dict(os.environ):
+            yield
+    else:
+        yield
diff --git a/tests/messages/test_setuptools_frontend.py b/tests/messages/test_setuptools_frontend.py
index d74c8e7a7..b55e8e3e8 100644
--- a/tests/messages/test_setuptools_frontend.py
+++ b/tests/messages/test_setuptools_frontend.py
@@ -48,13 +48,6 @@ def test_extract_distutils_keyword_arg_388(kwarg, expected):
     assert set(cmdinst.add_comments) == {"Bar", "Foo"}
 
 
-@pytest.mark.xfail(
-    # Python 3.10.16[pypy-7.3.19-final] in GHA fails with "unsupported locale setting"
-    # in the subprocesses this test spawns.  Hard to say why because it doesn't do that
-    # locally.
-    condition=(sys.implementation.name == "pypy" and "BABEL_TOX_INI_DIR" in os.environ),
-    reason="Test will likely fail with 'unsupported locale setting' in subprocesses; see comment",
-)
 def test_setuptools_commands(tmp_path, monkeypatch):
     """
     Smoke-tests all of the setuptools versions of the commands in turn.