diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..768dbcc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,6 @@
+CLAUDE.MD
+AGENTS.MD
+.projectmem/*
+__pycache__/*
+*.pyc
+.ruff_cache/*
\ No newline at end of file
diff --git a/codex_usage.py b/codex_usage.py
index b4f4437..250200a 100755
--- a/codex_usage.py
+++ b/codex_usage.py
@@ -38,8 +38,16 @@
 from pathlib import Path
 from typing import Any, Callable
 
-AUTH_PATH = Path("~/.codex/auth.json").expanduser()
-CODEX_HOME = Path("~/.codex").expanduser()
+
+def resolve_codex_home() -> Path:
+    codex_home = os.environ.get("CODEX_HOME")
+    if codex_home:
+        return Path(codex_home).expanduser()
+    return Path.home() / ".codex"
+
+
+CODEX_HOME = resolve_codex_home()
+AUTH_PATH = CODEX_HOME / "auth.json"
 SCRIPT_DIR = Path(__file__).resolve().parent
 EXPORT_DIR = SCRIPT_DIR
 API_BASE = "https://chatgpt.com/backend-api"
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/tests/__init__.py
@@ -0,0 +1 @@
+
diff --git a/tests/test_codex_paths.py b/tests/test_codex_paths.py
new file mode 100644
index 0000000..e42bc67
--- /dev/null
+++ b/tests/test_codex_paths.py
@@ -0,0 +1,55 @@
+import importlib
+import os
+import sys
+import unittest
+from pathlib import Path
+from unittest.mock import patch
+
+ROOT = Path(__file__).resolve().parents[1]
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
+
+codex_usage = importlib.import_module("codex_usage")
+
+
+class CodexPathTests(unittest.TestCase):
+    def reload_codex_usage(
+        self, *, codex_home: str | None = None, home: Path | None = None
+    ):
+        env = {"CODEX_HOME": codex_home} if codex_home is not None else {}
+
+        with patch.dict(os.environ, env, clear=False):
+            if codex_home is None:
+                os.environ.pop("CODEX_HOME", None)
+            if home is None:
+                module = importlib.reload(codex_usage)
+                return module, module.resolve_codex_home()
+            with patch.object(Path, "home", return_value=home):
+                module = importlib.reload(codex_usage)
+                return module, module.resolve_codex_home()
+
+    def tearDown(self) -> None:
+        importlib.reload(codex_usage)
+
+    def test_codex_home_uses_codex_home_environment_variable(self) -> None:
+        override = Path("C:/Users/Mike/AppData/Roaming/Codex")
+
+        module, resolved = self.reload_codex_usage(codex_home=str(override))
+
+        self.assertEqual(resolved, override)
+        self.assertEqual(module.CODEX_HOME, override)
+        self.assertEqual(module.AUTH_PATH, override / "auth.json")
+
+    def test_codex_home_defaults_to_dot_codex_under_home(self) -> None:
+        home = Path("C:/Users/Mike")
+        expected = home / ".codex"
+
+        module, resolved = self.reload_codex_usage(home=home)
+
+        self.assertEqual(resolved, expected)
+        self.assertEqual(module.CODEX_HOME, expected)
+        self.assertEqual(module.AUTH_PATH, expected / "auth.json")
+
+
+if __name__ == "__main__":
+    unittest.main()