diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index 3547fc2..1542386 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -11,6 +11,7 @@ python:
   install:
     - method: pip
       path: .
+    - requirements: docs/requirements.txt
 
 sphinx:
   configuration: docs/conf.py
diff --git a/docs/conf.py b/docs/conf.py
index fbae1f5..f9f8a26 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -6,6 +6,7 @@
     "sphinx.ext.autodoc",
     "sphinx.ext.intersphinx",
     "sphinx.ext.viewcode",
+    "sphinx_rtd_theme",
 ]
 
 intersphinx_mapping = {
diff --git a/docs/requirements.txt b/docs/requirements.txt
new file mode 100644
index 0000000..8213302
--- /dev/null
+++ b/docs/requirements.txt
@@ -0,0 +1,2 @@
+sphinx
+sphinx_rtd_theme
diff --git a/tox.ini b/tox.ini
index 0753d51..37b5bf8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -34,8 +34,7 @@ escription = format the code base to adhere to our styles, and complain about wh
 
 [testenv:docs]
 deps =
-    sphinx
-    sphinx_rtd_theme
+    -r docs/requirements.txt
 commands =
     sphinx-build -q -W -b html -d "{envtmpdir}{/}doctree" docs "{toxinidir}{/}dist{/}docs"
     python -c 'print(r"documentation available under file://{toxinidir}{/}dist{/}docs{/}index.html")'