diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 22723bdc6..d4c9771ca 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -92,11 +92,6 @@ jobs:
             python-version: "pypy-3.10"
           - os: "windows-latest"
             python-version: "pypy-3.10"
-          # TODO: 3.12 setlocale(...) is broken on Windows & Mac
-          - os: "macos-latest"
-            python-version: "3.12"
-          - os: "windows-latest"
-            python-version: "3.12"
     steps:
       - uses: actions/checkout@v3
         with:
diff --git a/changelog.d/+py312-setlocale-fail.infrastructure.md b/changelog.d/+py312-setlocale-fail.infrastructure.md
new file mode 100644
index 000000000..d13015278
--- /dev/null
+++ b/changelog.d/+py312-setlocale-fail.infrastructure.md
@@ -0,0 +1 @@
+Fixed tests failing because of changes made to `locale.normalize` in Python 3.12.
diff --git a/test/unit/b2http/test_b2http.py b/test/unit/b2http/test_b2http.py
index 4ab4da27b..d77c034a2 100644
--- a/test/unit/b2http/test_b2http.py
+++ b/test/unit/b2http/test_b2http.py
@@ -11,6 +11,7 @@
 
 import datetime
 import locale
+import sys
 from unittest.mock import MagicMock, call, patch
 
 import apiver_deps
@@ -306,9 +307,11 @@ class TestB2HttpUserAgentAppend(TestB2Http):
 
 class TestSetLocaleContextManager(TestBase):
     def test_set_locale_context_manager(self):
-        test_locale = locale.normalize(
-            'C.utf8'
-        )  # C.UTF-8 on Ubuntu 18.04 Bionic, C.utf8 on Ubuntu 22.04 Jammy
+        # C.UTF-8 on Ubuntu 18.04 Bionic, C.utf8 on Ubuntu 22.04 Jammy
+        # Neither macOS nor Windows have C.UTF-8 locale, and they use `en_US.UTF-8`.
+        # Since Python 3.12, locale.normalize no longer falls back
+        # to the `en_US` version, so we're providing it here manually.
+        test_locale = locale.normalize('C.UTF-8' if sys.platform == 'linux' else 'en_US.UTF-8')
         other_locale = 'C'
 
         saved = locale.setlocale(locale.LC_ALL)