diff --git a/phpseclib/Math/BigInteger.php b/phpseclib/Math/BigInteger.php
index fe1f43c5..f8315cb5 100644
--- a/phpseclib/Math/BigInteger.php
+++ b/phpseclib/Math/BigInteger.php
@@ -843,7 +843,7 @@ class BigInteger
             $opts[] = 'OpenSSL';
         }
         if (!empty($opts)) {
-            $engine.= ' (' . implode($opts, ', ') . ')';
+            $engine.= ' (' . implode('.', $opts) . ')';
         }
         return array(
             'value' => '0x' . $this->toHex(true),