diff --git a/phpseclib/Math/BigInteger/Engines/Engine.php b/phpseclib/Math/BigInteger/Engines/Engine.php
index e46e9609..474abe10 100644
--- a/phpseclib/Math/BigInteger/Engines/Engine.php
+++ b/phpseclib/Math/BigInteger/Engines/Engine.php
@@ -619,7 +619,7 @@ abstract class Engine implements \JsonSerializable
      */
     public function getLengthInBytes()
     {
-        return strlen($this->toBytes());
+        return (int) ceil($this->getLength() / 8);
     }
 
     /**
diff --git a/phpseclib/Math/BigInteger/Engines/PHP.php b/phpseclib/Math/BigInteger/Engines/PHP.php
index 7e85783e..2d895952 100644
--- a/phpseclib/Math/BigInteger/Engines/PHP.php
+++ b/phpseclib/Math/BigInteger/Engines/PHP.php
@@ -1341,4 +1341,17 @@ abstract class PHP extends Engine
         }
         return false;
     }
+
+    /**
+     * Return the size of a BigInteger in bits
+     *
+     * @return int
+     */
+    public function getLength()
+    {
+        $max = count($this->value) - 1;
+        return $max != -1 ?
+            $max * static::BASE + intval(ceil(log($this->value[$max] + 1, 2))) :
+            0;
+    }
 }
diff --git a/tests/Unit/File/ASN1Test.php b/tests/Unit/File/ASN1Test.php
index b39ce46d..0dd40edc 100644
--- a/tests/Unit/File/ASN1Test.php
+++ b/tests/Unit/File/ASN1Test.php
@@ -455,9 +455,8 @@ class ASN1Test extends PhpseclibTestCase
     {
         $cert = file_get_contents(dirname(__FILE__) . '/ASN1/mal-cert-02.der');
 
-        $asn1 = new ASN1();
-        $decoded = $asn1->decodeBER($cert);
-        $this->assertFalse($decoded[0]);
+        $decoded = ASN1::decodeBER($cert);
+        $this->assertNull($decoded);
 
         //$x509 = new X509();
         //$x509->loadX509($cert);