diff --git a/.gitignore b/.gitignore
index 1bbc728..33807df 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,5 @@
 .pytest_cache/
 __pycache__/
 dist/
+/.venv/
+/.hypothesis/
diff --git a/setup.cfg b/setup.cfg
new file mode 100644
index 0000000..43d7a3a
--- /dev/null
+++ b/setup.cfg
@@ -0,0 +1,2 @@
+[flake8]
+max-line-length = 90
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_smoke.py b/tests/test_smoke.py
new file mode 100644
index 0000000..218447a
--- /dev/null
+++ b/tests/test_smoke.py
@@ -0,0 +1,29 @@
+
+
+from io import StringIO
+from pathlib import Path
+import subprocess
+import sys
+from typeforce._cli import main
+
+
+def test_smoke(tmp_path: Path):
+    # create venv
+    venv_path = tmp_path / '.venv'
+    cmd = [sys.executable, '-m', 'venv', str(venv_path)]
+    subprocess.run(cmd, check=True)
+
+    # install deps
+    exe_path = venv_path / 'bin' / 'python'
+    cmd = [str(exe_path), '-m', 'pip', 'install', 'astroid']
+    subprocess.run(cmd, check=True)
+
+    # run typeforce
+    stdout = StringIO()
+    code = main(['--exe', str(exe_path)], stdout)
+    assert code == 0
+
+    stdout.seek(0)
+    output = stdout.read()
+    assert 'astroid' in output
+    assert 'patched' in output
diff --git a/typeforce/__init__.py b/typeforce/__init__.py
index bab1daf..c78bb87 100644
--- a/typeforce/__init__.py
+++ b/typeforce/__init__.py
@@ -1,4 +1,4 @@
 """CLI tool to propagate py.typed into third-party libraries.
 """
 
-__version__ = '0.2.0'
+__version__ = '0.2.1'
diff --git a/typeforce/_cli.py b/typeforce/_cli.py
index b72eda3..4af794d 100644
--- a/typeforce/_cli.py
+++ b/typeforce/_cli.py
@@ -6,8 +6,14 @@
 
 def main(argv: typing.List[str], stream: typing.TextIO) -> int:
     parser = ArgumentParser()
-    parser.add_argument('--exe', default=sys.executable)
-    parser.add_argument('--dry', action='store_true')
+    parser.add_argument(
+        '--exe', default=sys.executable,
+        help='path to python executable to patch',
+    )
+    parser.add_argument(
+        '--dry', action='store_true',
+        help='don\'t patch, only print changes',
+    )
     args = parser.parse_args(argv)
     explorer = Explorer(exe=args.exe, dry=args.dry)
     for line in explorer.run():
diff --git a/typeforce/_core.py b/typeforce/_core.py
index 947798e..7c3afe4 100644
--- a/typeforce/_core.py
+++ b/typeforce/_core.py
@@ -12,17 +12,7 @@
 
 MARKER = 'py.typed'
 TEMPLATE = '{name:30} {status}'
-SCRIPT = """
-import sys
-import {name} as module
-
-for name in dir(module):
-    obj = getattr(module, name)
-    ann = getattr(obj, '__annotations__', None)
-    if ann:
-        sys.exit(21)
-sys.exit(22)
-"""
+ROOT = Path(__file__).parent
 
 
 class Module(typing.NamedTuple):
@@ -36,12 +26,16 @@ def patched(self) -> bool:
 
     @property
     def stubbed(self) -> bool:
+        if self.path.name.endswith('-stubs'):
+            return True
         new_name = self.path.name + '-stubs'
         return (self.path.parent / new_name).exists()
 
     @property
     def annotated(self) -> bool:
-        script = SCRIPT.format(name=self.path.name)
+        script_path = ROOT / '_script_inspect.py'
+        script = script_path.read_text()
+        script = script.replace('MODULE_NAME', self.path.name)
         result = subprocess.run([self.exe, '-c', script])
         assert result.returncode in (21, 22)
         return result.returncode == 21
@@ -74,10 +68,17 @@ class Explorer(typing.NamedTuple):
 
     @property
     def root(self) -> Path:
-        cmd = [self.exe, '-c', 'print(__import__("site").USER_SITE)']
+        script_path = ROOT / '_script_sites.py'
+        cmd = [self.exe, str(script_path)]
         result = subprocess.run(cmd, check=True, stdout=subprocess.PIPE)
-        path = result.stdout.decode().strip()
-        return Path(path)
+        sites = result.stdout.decode().strip().splitlines()
+        print(sites)
+        for site in sites:
+            path = Path(site)
+            if path.exists():
+                print(path)
+                return path
+        raise LookupError('cannot find site packages directory')
 
     @property
     def modules(self) -> typing.Iterable[Module]:
diff --git a/typeforce/_script_inspect.py b/typeforce/_script_inspect.py
new file mode 100644
index 0000000..20cd2af
--- /dev/null
+++ b/typeforce/_script_inspect.py
@@ -0,0 +1,9 @@
+import sys
+import MODULE_NAME as module  # type: ignore[import]
+
+for name in dir(module):
+    obj = getattr(module, name)
+    ann = getattr(obj, '__annotations__', None)
+    if ann:
+        sys.exit(21)
+sys.exit(22)
diff --git a/typeforce/_script_sites.py b/typeforce/_script_sites.py
new file mode 100644
index 0000000..6f18721
--- /dev/null
+++ b/typeforce/_script_sites.py
@@ -0,0 +1,4 @@
+import site
+
+sites = site.getsitepackages() + [site.getusersitepackages()]
+print('\n'.join(sites))