diff --git a/tox.ini b/tox.ini
index 29be712..369b8d5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,29 +1,30 @@
 [tox]
 envlist=flake8
 
 [testenv]
 basepython = python3
 passenv = SPHINXOPTS JAVA_HOME
 
 [testenv:sphinx]
+extras =
+  building
 deps =
   django < 2
-  .[building]
   pifpaf
 commands =
   {envpython} -m pifpaf run postgresql -- make -C docs {posargs:html}
 
 [testenv:sphinx-dev]
 deps =
   django < 2
   -rrequirements-swh-dev.txt
   pifpaf
 commands =
   {envpython} -m pifpaf run postgresql -- make -C docs {posargs:html}
 
 [testenv:flake8]
 skip_install = true
 deps =
   flake8
 commands =
   {envpython} -m flake8