Index: tests/Zend/Form/Element/CaptchaTest.php
===================================================================
--- tests/Zend/Form/Element/CaptchaTest.php	(revision 24717)
+++ tests/Zend/Form/Element/CaptchaTest.php	(working copy)
@@ -105,6 +105,28 @@
     }
 
     /**
+     * @group ZF-12161
+     */
+    public function testSettingCustomCaptchaAdapterPerConstructor()
+    {
+        $element = new Zend_Form_Element_Captcha(
+            'foo',
+            array(
+                'prefixPath' => array(
+                    'prefix' => 'Zend_Form_Element_CaptchaTest',
+                    'path'   => dirname(__FILE__) . '/_files',
+                ),
+                'captcha' => 'Foo',
+            )
+        );
+
+        $this->assertInstanceOf(
+            'Zend_Form_Element_CaptchaTest_Captcha_Foo',
+            $element->getCaptcha()
+        );
+    }
+
+    /**
      * @see   ZF-4038
      * @group ZF-4038
      */
Index: tests/Zend/Form/Element/_files/Captcha/Foo.php
===================================================================
--- tests/Zend/Form/Element/_files/Captcha/Foo.php	(revision 0)
+++ tests/Zend/Form/Element/_files/Captcha/Foo.php	(revision 0)
@@ -0,0 +1,33 @@
+<?php
+/**
+ * Zend Framework
+ *
+ * LICENSE
+ *
+ * This source file is subject to the new BSD license that is bundled
+ * with this package in the file LICENSE.txt.
+ * It is also available through the world-wide-web at this URL:
+ * http://framework.zend.com/license/new-bsd
+ * If you did not receive a copy of the license and are unable to
+ * obtain it through the world-wide-web, please send an email
+ * to license@zend.com so we can send you a copy immediately.
+ *
+ * @category   Zend
+ * @package    Zend_Form
+ * @subpackage UnitTests
+ * @copyright  Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license    http://framework.zend.com/license/new-bsd     New BSD License
+ * @version    $Id: Foo.php 24593 2012-01-05 20:35:02Z matthew $
+ */
+
+/**
+ * @category   Zend
+ * @package    Zend_Form
+ * @subpackage UnitTests
+ * @copyright  Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license    http://framework.zend.com/license/new-bsd     New BSD License
+ */
+class Zend_Form_Element_CaptchaTest_Captcha_Foo extends Zend_Captcha_Dumb
+{
+
+}