diff --git a/tests/unit/optional_dependencies_test.py b/tests/unit/optional_dependencies_test.py
index 92f36d3..f67d64b 100644
--- a/tests/unit/optional_dependencies_test.py
+++ b/tests/unit/optional_dependencies_test.py
@@ -4,15 +4,19 @@ from __future__ import annotations
 
 import builtins
 import importlib
+import os
+import subprocess
 import sys
 from collections.abc import Callable, Mapping, Sequence
+from pathlib import Path
 from types import ModuleType
 from unittest.mock import patch
 
 import pytest
 
 import python_repositories
-from python_repositories import JsonRepositoryInterface
+
+_ROOT = Path(__file__).resolve().parents[2]
 
 
 def _block_backend_import(blocked_prefix: str) -> Callable[..., ModuleType]:
@@ -33,10 +37,23 @@ def _block_backend_import(blocked_prefix: str) -> Callable[..., ModuleType]:
 
 
 def test_base_import_does_not_load_adapters() -> None:
-    """Interfaces are available without loading adapter modules."""
-    assert JsonRepositoryInterface is not None
-    assert "python_repositories.adapters.redis_adapter" not in sys.modules
-    assert "python_repositories.adapters.minio_adapter" not in sys.modules
+    """Base package import does not eagerly load backend adapter modules."""
+    script = """
+import sys
+from python_repositories import JsonRepositoryInterface
+
+assert JsonRepositoryInterface is not None
+assert "python_repositories.adapters.redis_adapter" not in sys.modules
+assert "python_repositories.adapters.minio_adapter" not in sys.modules
+"""
+    result = subprocess.run(
+        [sys.executable, "-c", script],
+        cwd=_ROOT,
+        env={**os.environ, "PYTHONPATH": str(_ROOT)},
+        capture_output=True,
+        text=True,
+    )
+    assert result.returncode == 0, result.stderr or result.stdout
 
 
 def test_lazy_adapter_load_succeeds_when_extra_present() -> None: