diff --git a/.github/workflows/pages.yml b/.github/workflows/pages.yml
index a691bc7..c124356 100644
--- a/.github/workflows/pages.yml
+++ b/.github/workflows/pages.yml
@@ -8,7 +8,7 @@ on:
 
 jobs:
   pages:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
       - name: Install pandoc