diff --git a/requirements.txt b/requirements.txt
index 72bb60a81..8d21ef16b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,7 @@
-# pinning sphinx to 1.4.* due to search issues with rtd:
-# https://github.com/rtfd/readthedocs-sphinx-ext/issues/25
-sphinx ==1.4.*
+# Base dependencies
+
+# Sync with readthedocs:
+# https://github.com/readthedocs/readthedocs.org/blob/master/requirements/pip.txt
+# https://github.com/readthedocs/readthedocs.org/blob/master/requirements/local-docs-build.txt
+sphinx==1.8.5  # pyup: <2.0.0
+sphinx_rtd_theme==0.4.3