diff --git a/conftest.py b/conftest.py
index 222655643..757325d21 100644
--- a/conftest.py
+++ b/conftest.py
@@ -10,3 +10,7 @@ def environ():
     # [ERROR]: failed to download the file: HTTP Error 401: Unauthorized
     # https://github.com/ansible/ansible/issues/61666
     os.environ['NETRC'] = ''
+
+    # adds extra environment variables that may be needed during testing
+    if not os.environ.get('TEST_BASE_IMAGE', ""):
+        os.environ['TEST_BASE_IMAGE'] = 'docker.io/pycontribs/centos:7'
diff --git a/molecule/test/functional/docker/test_scenarios.py b/molecule/test/functional/docker/test_scenarios.py
index 294478781..fd12a8abd 100644
--- a/molecule/test/functional/docker/test_scenarios.py
+++ b/molecule/test/functional/docker/test_scenarios.py
@@ -221,7 +221,7 @@ def test_command_test_builds_local_molecule_image(
     scenario_to_test, with_scenario, scenario_name, driver_name
 ):
     try:
-        image = os.environ.get('TEST_BASE_IMAGE', "docker.io/pycontribs/centos:7")
+        image = os.environ['TEST_BASE_IMAGE']
         cmd = sh.docker.bake('rmi', 'molecule_local/{}'.format(image), '--force')
         pytest.helpers.run_command(cmd)
     except sh.ErrorReturnCode:
diff --git a/tox.ini b/tox.ini
index 72bd7d5e5..4cd2ce542 100644
--- a/tox.ini
+++ b/tox.ini
@@ -21,7 +21,6 @@ passenv = *
 setenv =
     ANSIBLE_CALLABLE_WHITELIST={env:ANSIBLE_CALLABLE_WHITELIST:timer,profile_roles}
     PYTHONDONTWRITEBYTECODE=1
-    TEST_BASE_IMAGE=docker.io/pycontribs/centos:7
     # -n auto used only on unit as is not supported by functional yet
     unit: PYTEST_ADDOPTS=molecule/test/unit/ --cov={toxinidir}/molecule/ --no-cov-on-fail {env:PYTEST_ADDOPTS:-n auto}
     functional: PYTEST_ADDOPTS=molecule/test/functional/ {env:PYTEST_ADDOPTS:}