diff --git a/.azure-pipelines/templates/jobs/standard-tests-jobs.yml b/.azure-pipelines/templates/jobs/standard-tests-jobs.yml
index a00994a94..6c4e23103 100644
--- a/.azure-pipelines/templates/jobs/standard-tests-jobs.yml
+++ b/.azure-pipelines/templates/jobs/standard-tests-jobs.yml
@@ -26,10 +26,10 @@ jobs:
           TOXENV: integration-certbot
         linux-oldest-tests-1:
           IMAGE_NAME: ubuntu-18.04
-          TOXENV: {acme,apache,apache-v2,certbot}-oldest
+          TOXENV: '{acme,apache,apache-v2,certbot}-oldest'
         linux-oldest-tests-2:
           IMAGE_NAME: ubuntu-18.04
-          TOXENV: {dns,nginx}-oldest
+          TOXENV: '{dns,nginx}-oldest'
         linux-py27:
           IMAGE_NAME: ubuntu-18.04
           PYTHON_VERSION: 2.7