diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1758728e..abeacf57 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -5,7 +5,7 @@ on: [push, pull_request]
 jobs:
   build:
     name: CI
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2