diff --git a/setup.cfg b/setup.cfg
index 78a3083..7c59e91 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -61,7 +61,7 @@ pep8 = flake8
 coverage = pytest-cov
 docs =
     sphinx
-    sphinx-rtd-theme
+    sphinx-rtd-theme==3.0.2
 release =
     bumpversion
     twine