diff --git a/library/Director/Web/Form/Element/Boolean.php b/library/Director/Web/Form/Element/Boolean.php
index dfa45cf9..b2402c78 100644
--- a/library/Director/Web/Form/Element/Boolean.php
+++ b/library/Director/Web/Form/Element/Boolean.php
@@ -43,7 +43,7 @@ class Boolean extends ZfSelect
      * @param string $key
      * @codingStandardsIgnoreStart
      */
-    protected function _filterValue(&$value, $key)
+    protected function _filterValue(&$value, &$key)
     {
         // @codingStandardsIgnoreEnd
         if ($value === true) {
diff --git a/library/Director/Web/Form/Element/DataFilter.php b/library/Director/Web/Form/Element/DataFilter.php
index 3ee096a2..1e946aa9 100644
--- a/library/Director/Web/Form/Element/DataFilter.php
+++ b/library/Director/Web/Form/Element/DataFilter.php
@@ -56,7 +56,7 @@ class DataFilter extends FormElement
      * @inheritdoc
      * @codingStandardsIgnoreStart
      */
-    protected function _filterValue(&$value, $key)
+    protected function _filterValue(&$value, &$key)
     {
         // @codingStandardsIgnoreEnd
         try {
diff --git a/library/Director/Web/Form/Element/ExtensibleSet.php b/library/Director/Web/Form/Element/ExtensibleSet.php
index 178c9068..e443b06d 100644
--- a/library/Director/Web/Form/Element/ExtensibleSet.php
+++ b/library/Director/Web/Form/Element/ExtensibleSet.php
@@ -54,7 +54,7 @@ class ExtensibleSet extends FormElement
     /**
      * @codingStandardsIgnoreStart
      */
-    protected function _filterValue(&$value, $key)
+    protected function _filterValue(&$value, &$key)
     {
         // @codingStandardsIgnoreEnd
         if (is_array($value)) {