diff --git a/phpseclib/Crypt/RSA.php b/phpseclib/Crypt/RSA.php
index 9670c01a..cd116b56 100644
--- a/phpseclib/Crypt/RSA.php
+++ b/phpseclib/Crypt/RSA.php
@@ -2423,7 +2423,7 @@ class RSA
         $db = $maskedDB ^ $dbMask;
         $lHash2 = substr($db, 0, $this->hLen);
         $m = substr($db, $this->hLen);
-        if ($lHash != $lHash2) {
+        if (!$this->_equals($lHash, $lHash2)) {
             user_error('Decryption error');
             return false;
         }
diff --git a/phpseclib/Math/BigInteger.php b/phpseclib/Math/BigInteger.php
index 075f0f34..32320b43 100644
--- a/phpseclib/Math/BigInteger.php
+++ b/phpseclib/Math/BigInteger.php
@@ -2908,7 +2908,7 @@ class BigInteger
         // (will always result in a smaller number.  ie. ~1 isn't 1111 1110 - it's 0)
         $temp = $this->toBytes();
         if ($temp == '') {
-            return '';
+            return $this->_normalize(new Math_BigInteger());
         }
         $pre_msb = decbin(ord($temp[0]));
         $temp = ~$temp;