diff --git a/phpseclib/Math/BigInteger/Engines/BCMath/Base.php b/phpseclib/Math/BigInteger/Engines/BCMath/Base.php
index 91efeb00..026cd86f 100644
--- a/phpseclib/Math/BigInteger/Engines/BCMath/Base.php
+++ b/phpseclib/Math/BigInteger/Engines/BCMath/Base.php
@@ -60,7 +60,7 @@ abstract class Base extends BCMath
      * @param string $class
      * @return \phpseclib\Math\BigInteger\Engines\BCMath
      */
-    public static function powModHelper(BCMath $x, BCMath $e, BCMath $n, $class)
+    protected static function powModHelper(BCMath $x, BCMath $e, BCMath $n, $class)
     {
         if (empty($e->value)) {
             $temp = new $class();
diff --git a/phpseclib/Math/BigInteger/Engines/PHP/Base.php b/phpseclib/Math/BigInteger/Engines/PHP/Base.php
index 3529906e..640d17c6 100644
--- a/phpseclib/Math/BigInteger/Engines/PHP/Base.php
+++ b/phpseclib/Math/BigInteger/Engines/PHP/Base.php
@@ -80,7 +80,7 @@ abstract class Base extends PHP
      * @param string $class
      * @return \phpseclib\Math\BigInteger\Engines\PHP
      */
-    public static function powModHelper(PHP $x, PHP $e, PHP $n, $class)
+    protected static function powModHelper(PHP $x, PHP $e, PHP $n, $class)
     {
         if (empty($e->value)) {
             $temp = new $class();