diff --git a/durationpy/__init__.pyi b/durationpy/__init__.pyi
new file mode 100644
index 0000000..61b460e
--- /dev/null
+++ b/durationpy/__init__.pyi
@@ -0,0 +1,6 @@
+import datetime
+
+def from_str(duration: str) -> datetime.timedelta: ...
+def to_str(delta: datetime.timedelta, extended: bool = ...) -> str: ...
+
+class DurationError(ValueError): ...
diff --git a/durationpy/py.typed b/durationpy/py.typed
new file mode 100644
index 0000000..e69de29
diff --git a/setup.py b/setup.py
index 2f68c23..18d2ae9 100644
--- a/setup.py
+++ b/setup.py
@@ -9,5 +9,6 @@
     download_url = 'https://github.com/icholy/durationpy/tarball/0.9',
     version      = '0.9',
     packages     = ['durationpy'],
+    package_data = {'durationpy': ['py.typed', '*.pyi']},
     license      = 'MIT'
 )