diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 28f0675..7b6b90c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -73,6 +73,8 @@ jobs:
         uses: actions/download-artifact@v3
         with: {name: python-distribution-files, path: dist/}
       - name: Run tests
+        env:
+          PYTHONUTF8: 1
         run: >-
           pipx run --python '${{ steps.setup-python.outputs.python-path }}'
           tox --installpkg '${{ needs.prepare.outputs.wheel-distribution }}'
diff --git a/tox.ini b/tox.ini
index b052330..89292e6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -15,6 +15,7 @@ setenv =
 passenv =
     HOME
     SETUPTOOLS_*
+    PYTHONUTF8
 extras =
     testing
 commands =