diff --git a/tox.ini b/tox.ini
--- a/tox.ini
+++ b/tox.ini
@@ -32,6 +32,6 @@
 [testenv:black]
 skip_install = true
 deps =
-  black
+  black==19.10b0
 commands =
-  {envpython} -m black --check swh
+  {envpython} -m black --exclude swh/web/tests/resources --check swh