diff --git a/tox.ini b/tox.ini
index 98c8f96..a7a8d37 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,31 +1,32 @@
 [tox]
 envlist=flake8,mypy,py3
 
 [testenv]
+extras =
+  testing
 deps =
-  .[testing]
   pytest-cov
   pifpaf
 commands =
   pifpaf run postgresql -- pytest --doctest-modules \
   !slow: --hypothesis-profile=fast \
   slow:  --hypothesis-profile=slow \
   prop:  -m property_based \
          {envsitepackagesdir}/swh/indexer \
          --cov={envsitepackagesdir}/swh/indexer \
          --cov-branch {posargs}
 
 [testenv:flake8]
 skip_install = true
 deps =
   flake8
 commands =
   {envpython} -m flake8
 
 [testenv:mypy]
-skip_install = true
+extras =
+  testing
 deps =
-  .[testing]
   mypy
 commands =
   mypy swh