diff --git a/dev-requirements.txt b/dev-requirements.txt
index 93d2845..58827ed 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -4,5 +4,5 @@
 requests
 tox >= 2.4.1
 twine >= 1.8.0
--e .[test,docstest,pep8test]
+-e .[test,docs,docstest,pep8test]
 -e vectors
diff --git a/rtd-requirements.txt b/rtd-requirements.txt
new file mode 100644
index 0000000..142b6ca
--- /dev/null
+++ b/rtd-requirements.txt
@@ -0,0 +1 @@
+-e .[docs]
diff --git a/setup.py b/setup.py
index 800e94d..b655816 100644
--- a/setup.py
+++ b/setup.py
@@ -296,12 +296,14 @@
         ":platform_python_implementation != 'PyPy'": ["cffi >= 1.7"],
 
         "test": test_requirements,
+        "docs": [
+            "sphinx >= 1.6.5",
+            "sphinx_rtd_theme",
+        ],
         "docstest": [
             "doc8",
             "pyenchant >= 1.6.11",
             "readme_renderer >= 16.0",
-            "sphinx >= 1.6.5",
-            "sphinx_rtd_theme",
             "sphinxcontrib-spelling >= 4.0.1",
         ],
         "pep8test": [
diff --git a/tox.ini b/tox.ini
index 03c4c07..6dfe1c7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -37,6 +37,7 @@
 
 [testenv:docs]
 extras =
+    docs
     docstest
 basepython = python2.7
 commands =