diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index c27461a..946ef57 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -26,7 +26,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-20.04, macos-13, windows-latest]
         python-version: ["3.6", "3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
         no-coverage: [0]
         include: