diff --git a/py/tox.ini b/py/tox.ini
index ccbd578b67741..a144861b1fdb5 100644
--- a/py/tox.ini
+++ b/py/tox.ini
@@ -6,6 +6,7 @@ skip_install = true
 deps =
   Jinja2==3.0.3
   Sphinx==1.8.2
+  -r requirements.txt
 
 commands = sphinx-build -b html -d ../build/docs/doctrees docs/source ../build/docs/api/py {posargs}