diff --git a/.gitignore b/.gitignore
index 5ca9148..9650884 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,11 +1,13 @@
 *.pyc
 *.sw?
 *~
 /.coverage
 /.coverage.*
 .eggs/
 __pycache__
 *.egg-info/
 version.txt
 build/
 dist/
+.mypy_cache/
+.tox/
diff --git a/mypy.ini b/mypy.ini
new file mode 100644
index 0000000..37a15a5
--- /dev/null
+++ b/mypy.ini
@@ -0,0 +1,3 @@
+[mypy]
+namespace_packages = True
+warn_unused_ignores = True
diff --git a/swh/__init__.py b/swh/__init__.py
index 69e3be5..f14e196 100644
--- a/swh/__init__.py
+++ b/swh/__init__.py
@@ -1 +1,4 @@
-__path__ = __import__('pkgutil').extend_path(__path__, __name__)
+from pkgutil import extend_path
+from typing import Iterable
+
+__path__ = extend_path(__path__, __name__)  # type: Iterable[str]
diff --git a/swh/mirror/__init__.py b/swh/mirror/__init__.py
index 69e3be5..f14e196 100644
--- a/swh/mirror/__init__.py
+++ b/swh/mirror/__init__.py
@@ -1 +1,4 @@
-__path__ = __import__('pkgutil').extend_path(__path__, __name__)
+from pkgutil import extend_path
+from typing import Iterable
+
+__path__ = extend_path(__path__, __name__)  # type: Iterable[str]
diff --git a/swh/mirror/forge/py.typed b/swh/mirror/forge/py.typed
new file mode 100644
index 0000000..1242d43
--- /dev/null
+++ b/swh/mirror/forge/py.typed
@@ -0,0 +1 @@
+# Marker file for PEP 561.
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..1c3bb1b
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,17 @@
+[tox]
+envlist=flake8,mypy
+
+[testenv:flake8]
+skip_install = true
+deps =
+  flake8
+commands =
+  {envpython} -m flake8
+
+[testenv:mypy]
+skip_install = true
+deps =
+  .[testing]
+  mypy
+commands =
+  mypy swh