diff --git a/phpseclib/Math/BigInteger.php b/phpseclib/Math/BigInteger.php
index 8752a835..c175ce4e 100644
--- a/phpseclib/Math/BigInteger.php
+++ b/phpseclib/Math/BigInteger.php
@@ -67,7 +67,7 @@
  * @author     Jim Wigginton <terrafrost@php.net>
  * @copyright  MMVI Jim Wigginton
  * @license    http://www.gnu.org/licenses/lgpl.txt
- * @version    $Id: BigInteger.php,v 1.33 2010-03-22 22:32:03 terrafrost Exp $
+ * @version    $Id: BigInteger.php,v 1.33 2010/03/22 22:32:03 terrafrost Exp $
  * @link       http://pear.php.net/package/Math_BigInteger
  */
 
@@ -596,9 +596,10 @@ class Math_BigInteger {
     {
         $hex = $this->toHex($twos_compliment);
         $bits = '';
-        for ($i = 0; $i < strlen($hex); $i+=8) {
+        for ($i = 0, $end = strlen($hex) & 0xFFFFFFF8; $i < $end; $i+=8) {
             $bits.= str_pad(decbin(hexdec(substr($hex, $i, 8))), 32, '0', STR_PAD_LEFT);
         }
+        $bits.= str_pad(decbin(hexdec(substr($hex, $end))), strlen($hex) & 7, '0', STR_PAD_LEFT);
         return $this->precision > 0 ? substr($bits, -$this->precision) : ltrim($bits, '0');
     }