diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index 5c2ab4e1..8b0683e1 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -13,6 +13,7 @@ formats: []
 # docs
 
 build:
+  os: ubuntu-20.04
   tools:
     python: "3.10"