diff --git a/docs/contribute.rst b/docs/contribute.rst
index cb66e26..db29c2d 100644
--- a/docs/contribute.rst
+++ b/docs/contribute.rst
@@ -21,7 +21,7 @@ Install sigal in development mode::
 Install additional dependencies for development (Sphinx, pytest), and optional
 dependencies::
 
-    pip install -r requirements.txt
+    pip install -e .\[all,tests\]
 
 Building the docs
 -----------------
diff --git a/docs/installation.rst b/docs/installation.rst
index e089871..8342786 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -8,7 +8,7 @@ With pip::
 
 Or to install with optional dependencies (listed below)::
 
-    $ pip install sigal\[all\]
+    $ pip install sigal\[all,tests\]
 
 To install the development version, see the :doc:`contribute`.
 
@@ -29,8 +29,8 @@ The mandatory dependencies are:
 - Pillow
 - Python Markdown
 
-There are also a number of optional dependencies for the :doc:`plugins`, listed
-in the ``requirements.txt`` file:
+There are also a number of optional dependencies for the :doc:`plugins`,
+installable with the ``[all]`` marker:
 
 - Brotli, zopfli (compress assets plugin)
 - Boto (upload to S3 plugin)
diff --git a/readthedocs.yml b/readthedocs.yml
index febce40..b4d0b25 100644
--- a/readthedocs.yml
+++ b/readthedocs.yml
@@ -1,8 +1,12 @@
 version: 2
 
+build:
+  image: latest
+
 python:
   version: 3.7
   install:
     - method: pip
       path: .
-    - requirements: requirements-doc.txt
+      extra_requirements:
+        - docs
diff --git a/requirements-doc.txt b/requirements-doc.txt
deleted file mode 100644
index 38f3862..0000000
--- a/requirements-doc.txt
+++ /dev/null
@@ -1,3 +0,0 @@
--r requirements.txt
-alabaster
-Sphinx
diff --git a/requirements.txt b/requirements.txt
deleted file mode 100644
index b037f6b..0000000
--- a/requirements.txt
+++ /dev/null
@@ -1,13 +0,0 @@
-blinker
-boto
-brotli
-click
-coverage
-feedgenerator
-Jinja2
-Markdown
-Pillow
-pilkit
-pytest
-pytest-cov
-zopfli
diff --git a/setup.cfg b/setup.cfg
index 2e933db..67bab00 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -38,6 +38,8 @@ install_requires =
 
 [options.extras_require]
 all = boto; brotli; feedgenerator; zopfli
+tests = pytest; pytest-cov
+docs = Sphinx; alabaster
 
 [options.packages.find]
 exclude =
diff --git a/tox.ini b/tox.ini
index 5452cb3..b9eef2d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,8 +9,9 @@ python =
     3.8: py38
 
 [testenv]
-deps =
-    -r {toxinidir}/requirements.txt
+extras =
+    all
+    tests
 commands = pytest --cov sigal --cov-report term-missing tests/
 
 [testenv:check]
@@ -28,8 +29,7 @@ commands =
 
 [testenv:doc]
 whitelist_externals = make
-deps =
-    -r {toxinidir}/requirements-doc.txt
+extras = docs
 usedevelop = true
 commands =
     make -C docs html