diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index bcabc9893..50b42d8f4 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -18,3 +18,4 @@ jobs:
     - run: npx tslint -c ionic-migration.json -p tsconfig.json
     - run: npm run test:ci
     - run: npm run build:prod
+    - run: result=$(find src -type f -iname '*.html' -exec grep -E 'class="[^"]+"[^>]+class="' {} \; | wc -l); test $result -eq 0