diff --git a/phpseclib/Crypt/Base.php b/phpseclib/Crypt/Base.php
index 9e38f5b2..c2091387 100644
--- a/phpseclib/Crypt/Base.php
+++ b/phpseclib/Crypt/Base.php
@@ -1001,7 +1001,7 @@ class Crypt_Base
                     break;
                 case CRYPT_MODE_CBC:
                     if (!defined('OPENSSL_RAW_DATA')) {
-                        $padding = str_repeat(chr($this->block_size), $this->block_size) ^ substr($ciphertext, -$block_size);
+                        $padding = str_repeat(chr($this->block_size), $this->block_size) ^ substr($ciphertext, -$this->block_size);
                         $plaintext.= openssl_encrypt($padding, $this->cipher_name_openssl_ecb, $this->key, true);
                     }
                     $plaintext = openssl_decrypt($ciphertext, $this->cipher_name_openssl, $this->key, $this->openssl_options, $this->decryptIV);