diff --git a/.github/workflows/python.yml b/.github/workflows/python.yml
index 89d2752..57a597f 100644
--- a/.github/workflows/python.yml
+++ b/.github/workflows/python.yml
@@ -13,6 +13,8 @@ jobs:
   build:
 
     runs-on: ubuntu-20.04
+    container:
+      image: python:2.7.18-buster
     strategy:
       matrix:
         python-version: [2.7, 3.9]