diff --git a/tox.ini b/tox.ini
index 4f15c8ea..381d8037 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,37 +1,37 @@
 [tox]
 envlist=black,flake8,mypy,py3
 
 [testenv]
 extras =
   testing
 deps =
   pytest-cov
 commands =
   pytest \
     slow:  --hypothesis-profile=swh-web \
     !slow: --hypothesis-profile=swh-web-fast \
       --cov {envsitepackagesdir}/swh/web --cov-branch {posargs} {envsitepackagesdir}/swh/web
 
 [testenv:flake8]
 skip_install = true
 deps =
   flake8
 commands =
   {envpython} -m flake8 \
     --exclude=.tox,.git,__pycache__,.eggs,*.egg,node_modules
 
 [testenv:mypy]
 setenv = DJANGO_SETTINGS_MODULE = swh.web.settings.development
 extras =
   testing
 deps =
   mypy
 commands =
   mypy swh
 
 [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