diff --git a/library/Zend/InputFilter/InputFilterPluginManager.php b/library/Zend/InputFilter/InputFilterPluginManager.php
index de1038aafc8..48170f92fa8 100644
--- a/library/Zend/InputFilter/InputFilterPluginManager.php
+++ b/library/Zend/InputFilter/InputFilterPluginManager.php
@@ -70,7 +70,7 @@ public function populateFactory($inputfilter)
      */
     public function validatePlugin($plugin)
     {
-        if ($plugin instanceof InputFilterInterface) {
+        if ($plugin instanceof InputFilterInterface || $plugin instanceof InputInterface) {
             // Hook to perform various initialization, when the inputfilter is not created through the factory
             if ($plugin instanceof InitializableInterface) {
                 $plugin->init();