diff --git a/wp-includes/sodium_compat/src/Core/Util.php b/wp-includes/sodium_compat/src/Core/Util.php
index a5808b191d..aa93dfd044 100644
--- a/wp-includes/sodium_compat/src/Core/Util.php
+++ b/wp-includes/sodium_compat/src/Core/Util.php
@@ -911,6 +911,7 @@ abstract class ParagonIE_Sodium_Core_Util
 
         if ($mbstring === null) {
             $mbstring = extension_loaded('mbstring')
+                && defined('MB_OVERLOAD_STRING')
                 &&
             ((int) (ini_get('mbstring.func_overload')) & MB_OVERLOAD_STRING);
         }
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 089215be4e..c2d58459c7 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.6-alpha-49056';
+$wp_version = '5.6-alpha-49057';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.