diff --git a/.azure-pipelines/templates/jobs/standard-tests-jobs.yml b/.azure-pipelines/templates/jobs/standard-tests-jobs.yml
index 6c4e23103..2e13bec21 100644
--- a/.azure-pipelines/templates/jobs/standard-tests-jobs.yml
+++ b/.azure-pipelines/templates/jobs/standard-tests-jobs.yml
@@ -26,9 +26,11 @@ jobs:
           TOXENV: integration-certbot
         linux-oldest-tests-1:
           IMAGE_NAME: ubuntu-18.04
+          PYTHON_VERSION: 3.6
           TOXENV: '{acme,apache,apache-v2,certbot}-oldest'
         linux-oldest-tests-2:
           IMAGE_NAME: ubuntu-18.04
+          PYTHON_VERSION: 3.6
           TOXENV: '{dns,nginx}-oldest'
         linux-py27:
           IMAGE_NAME: ubuntu-18.04