diff --git a/.readthedocs.yaml b/.readthedocs.yml
similarity index 96%
rename from .readthedocs.yaml
rename to .readthedocs.yml
index 4b12f640c..85a378c3b 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yml
@@ -13,6 +13,7 @@ sphinx:
 
 # Optionally set the version of Python and requirements required to build your docs
 python:
+  os: ubuntu-20.04
   version: "3.8"
   install:
     - method: pip