diff --git a/.github/workflows/master_merge.yml b/.github/workflows/master_merge.yml
index af3ac68..9bbf6ef 100644
--- a/.github/workflows/master_merge.yml
+++ b/.github/workflows/master_merge.yml
@@ -6,7 +6,7 @@ on:
 
 jobs:
   build-ckan-2-9:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2