diff --git a/Civi/Angular/Manager.php b/Civi/Angular/Manager.php
index ee5c65c4631fb3e329170c5adecb0589dd8f6191..ebe59aadd242478b5576fa01296b299d93f0d571 100644
--- a/Civi/Angular/Manager.php
+++ b/Civi/Angular/Manager.php
@@ -95,7 +95,9 @@ class Manager {
       foreach ($angularModules as $module => $info) {
         // This property must be an array. If null, set to the historical default of ['civicrm/a']
         // (historical default preserved for backward-compat reasons, but a better default would be the more common value of []).
-        $angularModules[$module]['basePages'] ??= ['civicrm/a'];
+        if (!isset($angularModules[$module]['basePages'])) {
+          $angularModules[$module]['basePages'] = ['civicrm/a'];
+        }
         if (!empty($info['settings'])) {
           \CRM_Core_Error::deprecatedWarning(sprintf('The Angular file "%s" from extension "%s" must be updated to use "settingsFactory" instead of "settings". See https://github.com/civicrm/civicrm-core/pull/19052', $info['module'], $info['ext']));
         }