diff --git a/pyproject.toml b/pyproject.toml
index 363a758..9df6bf9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -50,6 +50,7 @@ dev = [
     "pytest-cov>=4.0.0",
     "responses>=0.24.0",
     "ruff>=0.4.0",
+    "tomli>=2.0.0; python_version < '3.11'",
 ]
 all = [
     "hvac>=2.0.0",
diff --git a/tests/test_cli_edge_cases.py b/tests/test_cli_edge_cases.py
index a4ef9d1..dcd8c88 100644
--- a/tests/test_cli_edge_cases.py
+++ b/tests/test_cli_edge_cases.py
@@ -11,6 +11,11 @@
 
 from __future__ import annotations
 
+try:
+    import tomllib  # Python 3.11+
+except ModuleNotFoundError:  # Python 3.10
+    import tomli as tomllib
+
 import sys
 from pathlib import Path
 
@@ -26,7 +31,9 @@ def _make_config(tmp_path, env_map):
     """Create minimal .envault.yml with list-formatted environments."""
     config = {
         "project": "test",
-        "environments": [{"name": name, "env_file": path} for name, path in env_map.items()],
+        "environments": [
+            {"name": name, "env_file": path} for name, path in env_map.items()
+        ],
     }
     config_path = tmp_path / ".envault.yml"
     with open(config_path, "w") as f:
@@ -159,24 +166,26 @@ class TestPackagingQuality:
 
     def test_package_data_includes_py_typed(self):
         """pyproject.toml should have package-data config for py.typed."""
-        import tomllib
 
         pyproject = Path(__file__).parent.parent / "pyproject.toml"
         with open(pyproject, "rb") as f:
             data = tomllib.load(f)
         pkg_data = data.get("tool", {}).get("setuptools", {}).get("package-data", {})
-        assert "envault" in pkg_data, "Expected [tool.setuptools.package-data] section for 'envault'"
+        assert "envault" in pkg_data, (
+            "Expected [tool.setuptools.package-data] section for 'envault'"
+        )
         assert "py.typed" in pkg_data["envault"], (
             f"Expected 'py.typed' in package-data for envault, got {pkg_data['envault']}"
         )
 
     def test_ruff_known_first_party(self):
         """ruff known-first-party should be ['envault'], not ['*']."""
-        import tomllib
 
         pyproject = Path(__file__).parent.parent / "pyproject.toml"
         with open(pyproject, "rb") as f:
             data = tomllib.load(f)
-        isort_cfg = data.get("tool", {}).get("ruff", {}).get("lint", {}).get("isort", {})
+        isort_cfg = (
+            data.get("tool", {}).get("ruff", {}).get("lint", {}).get("isort", {})
+        )
         kfp = isort_cfg.get("known-first-party", [])
         assert kfp == ["envault"], f"known-first-party should be ['envault'], got {kfp}"