diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index c9ad01ef..2f4ec6b4 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -182,7 +182,8 @@ jobs:
         run: |
           $env:MSYS2_ROOT = msys2 -c 'cygpath -m /'
           $env:PATH = "$env:MSYS2_ROOT/ucrt64/bin;$env:PATH"
-          tox --env DISTUTILS_TEST_DEFAULT_COMPILER=mingw32
+          $env:DISTUTILS_TEST_DEFAULT_COMPILER = "mingw32"
+          tox
 
   ci_setuptools:
     # Integration testing with setuptools
diff --git a/conftest.py b/conftest.py
index c5db70ed..fd6cb6d6 100644
--- a/conftest.py
+++ b/conftest.py
@@ -173,7 +173,6 @@ def monkey_patch_get_default_compiler():
     from distutils import ccompiler
 
     default_compiler = os.environ.get("DISTUTILS_TEST_DEFAULT_COMPILER")
-    assert 0, default_compiler
 
     if default_compiler is not None:
 
diff --git a/tox.ini b/tox.ini
index d4bcc416..54835876 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,6 +5,8 @@ setenv =
 	PYTHONWARNDEFAULTENCODING = 1
 	# pypa/distutils#99
 	VIRTUALENV_NO_SETUPTOOLS = 1
+pass_env =
+	DISTUTILS_TEST_DEFAULT_COMPILER
 commands =
 	pytest {posargs}
 usedevelop = True