diff --git a/roles/add-build-sshkey/vars/main.yml b/roles/add-build-sshkey/vars/main.yaml
similarity index 100%
rename from roles/add-build-sshkey/vars/main.yml
rename to roles/add-build-sshkey/vars/main.yaml
diff --git a/roles/copy-build-sshkey/vars/main.yml b/roles/copy-build-sshkey/vars/main.yaml
similarity index 100%
rename from roles/copy-build-sshkey/vars/main.yml
rename to roles/copy-build-sshkey/vars/main.yaml
diff --git a/roles/ensure-docker/handlers/main.yml b/roles/ensure-docker/handlers/main.yaml
similarity index 100%
rename from roles/ensure-docker/handlers/main.yml
rename to roles/ensure-docker/handlers/main.yaml
diff --git a/roles/ensure-tox/defaults/main.yml b/roles/ensure-tox/defaults/main.yaml
similarity index 100%
rename from roles/ensure-tox/defaults/main.yml
rename to roles/ensure-tox/defaults/main.yaml
diff --git a/roles/remove-build-sshkey/tasks/main.yml b/roles/remove-build-sshkey/tasks/main.yaml
similarity index 100%
rename from roles/remove-build-sshkey/tasks/main.yml
rename to roles/remove-build-sshkey/tasks/main.yaml
diff --git a/roles/remove-build-sshkey/vars/main.yml b/roles/remove-build-sshkey/vars/main.yaml
similarity index 100%
rename from roles/remove-build-sshkey/vars/main.yml
rename to roles/remove-build-sshkey/vars/main.yaml
diff --git a/tox.ini b/tox.ini
index b10fad675..662b8e116 100644
--- a/tox.ini
+++ b/tox.ini
@@ -48,6 +48,8 @@ commands =
     ansible-playbook --syntax-check -i {toxinidir}/tests/inventory \{\} + > /dev/null"
   {toxinidir}/tools/check_jobs_documented.py
   {toxinidir}/tools/update-test-platforms.py
+  bash -c "(( $(find playbooks -name *.yml | wc -l) == 0)) || \{ echo 'Use .yaml'; exit 1; \}"
+  bash -c "(( $(find roles -name *.yml | wc -l) == 0)) || \{ echo 'Use .yaml'; exit 1; \}"
   bash -c "git diff --quiet || \{ echo 'ERROR: git in dirty status, reporting as failure'; exit 1; \}"
 
 [testenv:venv]