diff --git a/test/conftest.py b/test/conftest.py
new file mode 100644
index 0000000..dc8fac7
--- /dev/null
+++ b/test/conftest.py
@@ -0,0 +1,29 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#################################|###|#####################################
+#  __                            |   |                                    #
+# |  |--.--.--.----.-----.-----. |===| This file is part of Byron v0.8    #
+# |  _  |  |  |   _|  _  |     | |___| An evolutionary optimizer & fuzzer #
+# |_____|___  |__| |_____|__|__|  ).(  https://github.com/squillero/byron #
+#       |_____|                   \|/                                     #
+################################## ' ######################################
+# Copyright 2023 Giovanni Squillero and Alberto Tonda
+# SPDX-License-Identifier: Apache-2.0
+import pytest
+
+
+def pytest_addoption(parser):
+    parser.addoption("--all", action="store_true", default=False, help="run all tests (including 'avoidable' ones)")
+
+
+def pytest_configure(config):
+    config.addinivalue_line("markers", "avoidable: mark test as avoidable (require --all)")
+
+
+def pytest_collection_modifyitems(config, items):
+    if config.getoption("--all"):
+        return
+    skip_avoidable = pytest.mark.skip(reason="need --all option to run")
+    for item in items:
+        if "avoidable" in item.keywords:
+            item.add_marker(skip_avoidable)
diff --git a/test/runs/test_evaluators.py b/test/runs/test_evaluators.py
index bf561b1..e0423b1 100644
--- a/test/runs/test_evaluators.py
+++ b/test/runs/test_evaluators.py
@@ -10,6 +10,8 @@
 # Copyright 2023 Giovanni Squillero and Alberto Tonda
 # SPDX-License-Identifier: Apache-2.0
 
+import pytest
+
 import logging
 import itertools
 import os
@@ -25,6 +27,7 @@ def fitness(genotype):
     return sum(b == '1' for b in genotype)
 
 
+@pytest.mark.avoidable
 def test_evaluators():
     assert os.path.exists('runs') or os.path.exists('test/runs')
     if os.path.exists('test/runs'):