diff --git a/tests/Unit/Crypt/AES/TestCase.php b/tests/Unit/Crypt/AES/TestCase.php
index 0550b4e2..d89516ea 100644
--- a/tests/Unit/Crypt/AES/TestCase.php
+++ b/tests/Unit/Crypt/AES/TestCase.php
@@ -388,7 +388,7 @@ abstract class Unit_Crypt_AES_TestCase extends PhpseclibTestCase
      */
     public function testContinuousBuffer()
     {
-        $aes = new AES();
+        $aes = new AES(AES::MODE_CBC);
         $aes->disablePadding();
         $aes->enableContinuousBuffer();
         $aes->setIV(pack('H*', '0457bdb4a6712986688349a29eb82535'));