diff --git a/tests/Unit/Crypt/AES/McryptTest.php b/tests/Unit/Crypt/AES/McryptTest.php
index f1df6227..4327c7ea 100644
--- a/tests/Unit/Crypt/AES/McryptTest.php
+++ b/tests/Unit/Crypt/AES/McryptTest.php
@@ -9,6 +9,10 @@ class Unit_Crypt_AES_McryptTest extends Unit_Crypt_AES_TestCase
 {
     static public function setUpBeforeClass()
     {
+        if (!extension_loaded('mcrypt')) {
+            self::markTestSkipped('mcrypt extension is not available.');
+        }
+
         parent::setUpBeforeClass();
 
         self::ensureConstant('CRYPT_AES_MODE', CRYPT_AES_MODE_MCRYPT);