diff --git a/doc/requirements.txt b/doc/requirements.txt
index 4bed15c4df..0db3ae5bac 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,6 +1,6 @@
 # Requirements file for pip
 # list of Python packages used in documentation build
-sphinx==1.7.9
+sphinx
 sphinx-rtd-theme
 breathe
 nbsphinx