diff --git a/tox.ini b/tox.ini
--- a/tox.ini
+++ b/tox.ini
@@ -9,6 +9,7 @@
   swh.core[http] >= 0.0.61
   .[testing]
   pytest-cov
+  pyblake2
 commands =
   pytest --cov=swh --cov-branch {posargs}