diff --git a/src/mvt/common/config.py b/src/mvt/common/config.py
index 24bf4072..fc4b2ea5 100644
--- a/src/mvt/common/config.py
+++ b/src/mvt/common/config.py
@@ -12,7 +12,9 @@ from pydantic_settings import (
     YamlConfigSettingsSource,
 )
 
-MVT_CONFIG_FOLDER = user_config_dir("mvt")
+# MVT_CONFIG_FOLDER in the environment relocates the settings file, so that
+# a test run or a scripted install never touches the user's own.
+MVT_CONFIG_FOLDER = os.environ.get("MVT_CONFIG_FOLDER") or user_config_dir("mvt")
 MVT_CONFIG_PATH = os.path.join(MVT_CONFIG_FOLDER, "config.yaml")
 
 
diff --git a/src/mvt/common/indicators.py b/src/mvt/common/indicators.py
index 94afadf1..3886e34f 100644
--- a/src/mvt/common/indicators.py
+++ b/src/mvt/common/indicators.py
@@ -18,7 +18,9 @@ from appdirs import user_data_dir
 from .config import settings
 from .url import URL
 
-MVT_DATA_FOLDER = user_data_dir("mvt")
+# MVT_DATA_FOLDER in the environment relocates the downloaded indicators and
+# the update-check state kept next to them.
+MVT_DATA_FOLDER = os.environ.get("MVT_DATA_FOLDER") or user_data_dir("mvt")
 MVT_INDICATORS_FOLDER = os.path.join(MVT_DATA_FOLDER, "indicators")
 
 logger = logging.getLogger(__name__)
@@ -71,7 +73,9 @@ class Indicators:
             if os.path.isfile(path) and path.lower().endswith(".stix2"):
                 self.parse_stix2(path)
             elif os.path.isdir(path):
-                for file in glob.glob(os.path.join(path, "**", "*.stix2"), recursive=True):
+                for file in glob.glob(
+                    os.path.join(path, "**", "*.stix2"), recursive=True
+                ):
                     self.parse_stix2(file)
             else:
                 self.log.error(
@@ -518,9 +522,7 @@ class Indicators:
         the original URL order.
         """
         batches = [list(urls) if urls else [] for urls in url_batches]
-        unique_urls = list(
-            dict.fromkeys(url for urls in batches for url in urls)
-        )
+        unique_urls = list(dict.fromkeys(url for urls in batches for url in urls))
 
         if not unique_urls:
             return [None] * len(batches)
diff --git a/tests/conftest.py b/tests/conftest.py
index 06a890a9..40a084a8 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -3,20 +3,26 @@
 # Use of this software is governed by the MVT License 1.1 that can be found at
 #   https://license.mvt.re/1.1/
 
+import atexit
 import logging
 import os
+import shutil
+import tempfile
 
 import pytest
 
-from mvt.common.cli_plugins import (
-    MVT_ANDROID_CUSTOM_COMMANDS_ENV,
-    MVT_CUSTOM_COMMANDS_ENV,
-    MVT_IOS_CUSTOM_COMMANDS_ENV,
-)
-from mvt.common.indicators import Indicators
-
 from .artifacts.generate_stix import generate_test_stix_file
 
+# The suite must neither read nor write the developer's own MVT settings,
+# downloaded indicators or update-check state, and mvt.common.config saves
+# the settings file as soon as it is imported. Both folders are redirected
+# before any mvt module is imported, which is why this file imports none at
+# the top; the subprocesses the tests start inherit the variables.
+MVT_TEST_HOME = tempfile.mkdtemp(prefix="mvt-tests-")
+atexit.register(shutil.rmtree, MVT_TEST_HOME, ignore_errors=True)
+os.environ["MVT_CONFIG_FOLDER"] = os.path.join(MVT_TEST_HOME, "config")
+os.environ["MVT_DATA_FOLDER"] = os.path.join(MVT_TEST_HOME, "data")
+
 
 @pytest.fixture(scope="session", autouse=True)
 def indicator_file(request, tmp_path_factory):
@@ -47,6 +53,8 @@ def indicators_factory(indicator_file):
         android_property_names=[],
         files_sha256=[],
     ):
+        from mvt.common.indicators import Indicators
+
         ind = Indicators(log=logging.getLogger())
         ind.parse_stix2(indicator_file)
 
@@ -77,6 +85,11 @@ def restore_cli_commands(monkeypatch):
     """
     from mvt.android.cli import cli as android_cli
     from mvt.cli import cli as neutral_cli
+    from mvt.common.cli_plugins import (
+        MVT_ANDROID_CUSTOM_COMMANDS_ENV,
+        MVT_CUSTOM_COMMANDS_ENV,
+        MVT_IOS_CUSTOM_COMMANDS_ENV,
+    )
     from mvt.ios.cli import cli as ios_cli
 
     groups = (neutral_cli, ios_cli, android_cli)