diff --git a/phpseclib/Crypt/RSA.php b/phpseclib/Crypt/RSA.php
index 910c3a88..5d1d2405 100644
--- a/phpseclib/Crypt/RSA.php
+++ b/phpseclib/Crypt/RSA.php
@@ -502,7 +502,7 @@ class Crypt_RSA {
                             define('CRYPT_RSA_MODE', CRYPT_RSA_MODE_OPENSSL);
                     }
                     break;
-                default:
+                case true:
                     define('CRYPT_RSA_MODE', CRYPT_RSA_MODE_INTERNAL);
             }
         }