diff --git a/CHANGELOG.md b/CHANGELOG.md
index 82e0027..b5903e0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,9 @@
 - Switch to [Poetry](https://python-poetry.org/) for dependency and release management.
 - Chain exceptions using `raise new_exception from old_exception`
   ([#157](https://github.com/sybrenstuvel/python-rsa/pull/157))
+- Added marker file for PEP 561. This will allow type checking tools in dependent projects
+  to use type annotations from Python-RSA
+  ([#136](https://github.com/sybrenstuvel/python-rsa/pull/136)).
 
 ## Version 4.7.2 - released 2021-02-24
 
diff --git a/rsa/py.typed b/rsa/py.typed
new file mode 100644
index 0000000..6c27071
--- /dev/null
+++ b/rsa/py.typed
@@ -0,0 +1 @@
+# Marker file for PEP 561.  The rsa package uses inline types.