diff --git a/src/Pecee/Http/Input/InputHandler.php b/src/Pecee/Http/Input/InputHandler.php
index 69690dc..6d02116 100644
--- a/src/Pecee/Http/Input/InputHandler.php
+++ b/src/Pecee/Http/Input/InputHandler.php
@@ -313,7 +313,7 @@ class InputHandler
         $output = (\count($filter) > 0) ? array_intersect_key($output, array_flip($filter)) : $output;
 
         foreach ($filter as $filterKey) {
-            if (!array_key_exists($filterKey, $output)) {
+            if (array_key_exists($filterKey, $output) === false) {
                 $output[$filterKey] = null;
             }
         }
@@ -354,4 +354,4 @@ class InputHandler
         $this->file[$key] = $item;
     }
 
-}
\ No newline at end of file
+}