diff --git a/.github/workflows/python-package.yml b/.github/workflows/python-package.yml
index 931805f8..d3f9b1a8 100644
--- a/.github/workflows/python-package.yml
+++ b/.github/workflows/python-package.yml
@@ -11,8 +11,7 @@ on:
 
 jobs:
   build:
-
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         python-version: ['2.7', '3.5', '3.6', '3.7', '3.8', '3.9', 'pypy3']