diff --git a/.gitignore b/.gitignore
index da98680..f9ef9a5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,12 +1,13 @@
 *.egg-info/
 *.pyc
 *.sw?
 *~
 .coverage
 .eggs/
 .mypy_cache
 .tox
 __pycache__
 build/
 dist/
 version.txt
+.mypy_cache/
diff --git a/mypy.ini b/mypy.ini
new file mode 100644
index 0000000..46f8db8
--- /dev/null
+++ b/mypy.ini
@@ -0,0 +1,15 @@
+[mypy]
+namespace_packages = True
+warn_unused_ignores = True
+
+
+# 3rd party libraries without stubs (yet)
+
+[mypy-pkg_resources.*]
+ignore_missing_imports = True
+
+[mypy-pytest.*]
+ignore_missing_imports = True
+
+# [mypy-add_your_lib_here.*]
+# ignore_missing_imports = True
diff --git a/swh/foo/py.typed b/swh/foo/py.typed
new file mode 100644
index 0000000..1242d43
--- /dev/null
+++ b/swh/foo/py.typed
@@ -0,0 +1 @@
+# Marker file for PEP 561.
diff --git a/tox.ini b/tox.ini
index 335f4ed..2b5b085 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,23 +1,31 @@
 [tox]
 envlist=check-manifest,flake8,py3
 
 [testenv:py3]
 deps =
   .[testing]
   pytest-cov
 commands =
   pytest --cov=swh --cov-branch {posargs}
 
 [testenv:flake8]
 skip_install = true
 deps =
   flake8
 commands =
   {envpython} -m flake8
 
 [testenv:check-manifest]
 skip_install = true
 deps =
   check-manifest
 commands =
   {envpython} -m check_manifest {toxinidir}
+
+[testenv:mypy]
+skip_install = true
+deps =
+  .[testing]
+  mypy
+commands =
+  mypy swh