diff --git a/phpseclib/Math/BigInteger.php b/phpseclib/Math/BigInteger.php
index 3524668e..c6609e4d 100644
--- a/phpseclib/Math/BigInteger.php
+++ b/phpseclib/Math/BigInteger.php
@@ -136,7 +136,7 @@ class BigInteger implements \JsonSerializable
     {
         if (!isset(self::$mainEngine)) {
             $engines = [
-                ['GMP'],
+                ['GMP', ['DefaultEngine']],
                 ['PHP64', ['OpenSSL']],
                 ['BCMath', ['OpenSSL']],
                 ['PHP32', ['OpenSSL']],
@@ -145,7 +145,7 @@ class BigInteger implements \JsonSerializable
             ];
             foreach ($engines as $engine) {
                 try {
-                    self::setEngine($engine[0], isset($engine[1]) ? $engine[1] : []);
+                    self::setEngine($engine[0], $engine[1]);
                     break;
                 } catch (\Exception $e) {
                 }