diff --git a/.github/workflows/pythonapp.yml b/.github/workflows/pythonapp.yml
index e0acff36..7d6ae2c3 100644
--- a/.github/workflows/pythonapp.yml
+++ b/.github/workflows/pythonapp.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-latest, ubuntu-latest, windows-latest]
+        os: [macos-latest, ubuntu-20.04, windows-latest]
         python-version: ["3.6", "3.7", "3.8", "3.9", "3.10", "3.11"]
 
     steps: