diff --git a/tox.ini b/tox.ini
index 557eb85..76b70ee 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,30 +1,31 @@
 [tox]
 envlist=flake8,mypy,py3
 
-[testenv:py3]
+[testenv]
+extras =
+  testing
 deps =
-  .[testing]
   pytest-cov
 whitelist_externals =
   mvn
   sh
 commands =
   sh -c 'if ! [ -d {envdir}/share/swh-graph ]; then mvn -f java/pom.xml compile assembly:single; mkdir {envdir}/share/swh-graph; cp java/target/*.jar {envdir}/share/swh-graph; fi'
   pytest --cov={envsitepackagesdir}/swh/graph \
          {envsitepackagesdir}/swh/graph \
          --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