diff --git a/src/View/Helper/FormHelper.php b/src/View/Helper/FormHelper.php
index <HASH>..<HASH> 100644
--- a/src/View/Helper/FormHelper.php
+++ b/src/View/Helper/FormHelper.php
@@ -156,7 +156,9 @@ class FormHelper extends Helper
         if (array_key_exists('class', $options)) {
             $optionsClass = is_array($options['class']) ? $options['class'] : explode(' ', $options['class']);
             $class = array_unique(array_merge($class, $optionsClass));
+            unset($options['class']);
         }
+
         $options = Hash::merge($options, ['class' => $class]);
 
         return parent::submit($caption, $options);
Unset class to avoid re-merging.