diff --git a/tox.ini b/tox.ini
index 6b0c293..5f7972a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,8 +7,11 @@ commands =
     coverage run -m unittest discover -t . -s test
     coverage report
     coverage xml
+    # mypy won't install on PyPy, so only run the typechecking on CPython
+    !pypy3: mypy contextlib2
 deps =
     coverage
+    !pypy3: mypy
 
 [gh-actions]
 python =