diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index c88d6df..c7fca14 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -2,7 +2,7 @@ name: tests
 on: [push, pull_request]
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         python-version: ["3.6", "3.7", "3.8", "3.9", "3.10"]