diff --git a/.readthedocs.yml b/.readthedocs.yml
index 8a5af32f..58afb426 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -2,10 +2,12 @@
 version: 2
 formats: all
 
-python:
-  # Keep version in sync with tox.ini (docs and gh-actions).
-  version: "3.10"
+build:
+  os: ubuntu-20.04
+  tools:
+    python: "3.10"
 
+python:
   install:
     - method: pip
       path: .