diff --git a/framework/Core/lib/Horde/Registry.php b/framework/Core/lib/Horde/Registry.php
index 0b326b72bb7..032fb52d4b9 100644
--- a/framework/Core/lib/Horde/Registry.php
+++ b/framework/Core/lib/Horde/Registry.php
@@ -593,6 +593,7 @@ public function setAuthenticationSetting($authentication)
     {
         $this->_args['authentication'] = $authentication;
         $this->_cache['cfile'] = $this->_cache['ob'] = array();
+        $this->_cache['isauth'] = array();
         $this->_appsInit = array();
         while ($this->popApp());
     }