diff --git a/readthedocs.yml b/readthedocs.yml
index a24c500806..8a98f6c89a 100644
--- a/readthedocs.yml
+++ b/readthedocs.yml
@@ -1,6 +1,7 @@
 version: 2
 sphinx:
   configuration: docs/conf.py
+os: ubuntu-20.04
 python:
     version: 3.6
     install: