diff --git a/lib/core/public/load.js b/lib/core/public/load.js
index ea69f3b69..b38bc941f 100644
--- a/lib/core/public/load.js
+++ b/lib/core/public/load.js
@@ -32,6 +32,13 @@ function runCommand(data, keepalive, callback) {
 
   switch (data.command) {
     case 'rules':
+      // [a11y-core]: rules are registered per-frame
+      if (
+        typeof a11yEngine !== 'undefined' &&
+        typeof a11yEngine.ensureConfigured === 'function'
+      ) {
+        a11yEngine.ensureConfigured(options);
+      }
       return runRules(
         context,
         options,