diff --git a/setup.py b/setup.py
index 172dc4b..5ad80b5 100644
--- a/setup.py
+++ b/setup.py
@@ -1,37 +1,38 @@
 import os
 from setuptools import setup, find_packages
 
 
 def parse_requirements(name=None):
     if name:
         reqf = 'requirements-%s.txt' % name
     else:
         reqf = 'requirements.txt'
 
     requirements = []
     if not os.path.exists(reqf):
         return requirements
 
     with open(reqf) as f:
         for line in f.readlines():
             line = line.strip()
             if not line or line.startswith('#'):
                 continue
             requirements.append(line)
     return requirements
 
 
 setup(
     name='swh.docs',
     description='Software Heritage development documentation',
     author='Software Heritage developers',
     author_email='swh-devel@inria.fr',
     url='https://forge.softwareheritage.org/source/swh-docs/',
     packages=find_packages(),
     scripts=[],
-    install_requires=parse_requirements() + parse_requirements('swh'),
+    install_requires=parse_requirements(),
     setup_requires=['vcversioner'],
-    extras_require={'testing': parse_requirements('test')},
+    extras_require={'testing': parse_requirements('test'),
+                    'building': parse_requirements('swh')},
     vcversioner={},
     include_package_data=True,
 )
diff --git a/tox.ini b/tox.ini
index 31b1555..5be833c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,29 +1,29 @@
 [tox]
 envlist=flake8
 
 [testenv]
 basepython = python3
 passenv = SPHINXOPTS
 
 [testenv:sphinx]
 deps =
   django < 2
-  .[testing]
+  .[building]
   pifpaf
 commands =
-  {envpython} -m pifpaf run postgresql -- make -C docs html
+  {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 html
+  {envpython} -m pifpaf run postgresql -- make -C docs {posargs:html}
 
 [testenv:flake8]
 skip_install = true
 deps =
   flake8
 commands =
   {envpython} -m flake8