diff --git a/pyproject.toml b/pyproject.toml
index 08e11c1f..8945f9d6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -54,6 +54,7 @@ minversion = "7.0"
 addopts = """
 --strict-config
 --strict-markers
+--import-mode=importlib
 -ra
 -v
 -m 'not externalfile'
diff --git a/tests/conftest.py b/tests/conftest.py
index d446b30e..5a857913 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -2,16 +2,17 @@
 # Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
 
 import os
+import sys
 from pathlib import Path
 from typing import Any, List
 
 import pytest
 import scipp as sc
 
-# Load the config file in the test dir instead of the user's.
-os.environ['SCIPPDIR'] = os.fspath(Path(__file__).resolve().parent)
 # Silence warning from Jupyter
 os.environ['JUPYTER_PLATFORM_DIRS'] = '1'
+# To import helper modules
+sys.path.insert(0, str(Path(__file__).resolve().parent))
 
 pytest.register_assert_rewrite('scipp.testing.assertions')