diff --git a/phpseclib/Crypt/RSA.php b/phpseclib/Crypt/RSA.php
index 5552a3bd..16d21dcb 100644
--- a/phpseclib/Crypt/RSA.php
+++ b/phpseclib/Crypt/RSA.php
@@ -539,6 +539,7 @@ class Crypt_RSA
                         case !isset($versions['Header']):
                         case !isset($versions['Library']):
                         case $versions['Header'] == $versions['Library']:
+                        case version_compare($versions['Header'], '1.0.0') >= 0 && version_compare($versions['Library'], '1.0.0') >= 0:
                             define('CRYPT_RSA_MODE', CRYPT_RSA_MODE_OPENSSL);
                             break;
                         default:
diff --git a/phpseclib/Math/BigInteger.php b/phpseclib/Math/BigInteger.php
index d09677ac..cd495a2a 100644
--- a/phpseclib/Math/BigInteger.php
+++ b/phpseclib/Math/BigInteger.php
@@ -286,6 +286,7 @@ class Math_BigInteger
                 case !isset($versions['Header']):
                 case !isset($versions['Library']):
                 case $versions['Header'] == $versions['Library']:
+                case version_compare($versions['Header'], '1.0.0') >= 0 && version_compare($versions['Library'], '1.0.0') >= 0:
                     define('MATH_BIGINTEGER_OPENSSL_ENABLED', true);
                     break;
                 default: