diff --git a/alfort/py.typed b/alfort/py.typed
new file mode 100644
index 0000000..e69de29
diff --git a/pyproject.toml b/pyproject.toml
index 1a634b5..0f48fe2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,6 +4,7 @@ version = "0.0.0-dev"
 description = ""
 authors = ["Masahiro Wada <argon.argon.argon@gmail.com>"]
 license = "Apache-2.0"
+include = ["alfort/py.typed"]
 
 [tool.poetry.dependencies]
 python = "^3.10"