diff --git a/python/tox.ini b/python/tox.ini
index a1d26c4a1..3309b08a3 100644
--- a/python/tox.ini
+++ b/python/tox.ini
@@ -47,7 +47,7 @@ commands =
 [testenv:doc]
 changedir=doc
 deps =
-    sphinx==2.2.0
+    sphinx
     breathe
 commands =
     sphinx-build -Q -w toxdoc-warnings.log -b html . _build/html