diff --git a/setup.py b/setup.py
index 8d177d3..61e5973 100644
--- a/setup.py
+++ b/setup.py
@@ -4,4 +4,5 @@
 
 setup(
     name="mistune",
+    package_data={"mistune": ["py.typed", ]}
 )
diff --git a/src/mistune/py.typed b/src/mistune/py.typed
new file mode 100644
index 0000000..fd3375c
--- /dev/null
+++ b/src/mistune/py.typed
@@ -0,0 +1,2 @@
+# when type checking dependents, tell type checkers, e.g. mypy, to use this package's types
+# without this file, mypy will write a warning and ignore type annotations from mistune.