diff --git a/classes/Tools.php b/classes/Tools.php
index 9c7072e4f..cfad3fbb5 100644
--- a/classes/Tools.php
+++ b/classes/Tools.php
@@ -973,6 +973,8 @@ class ToolsCore
 			$str = mb_strtolower($str, 'utf-8');
 
 		$str = trim($str);
+		if (!function_exists('mb_strtolower'))
+			$str = Tools::replaceAccentedChars($str);
 
 		// Remove all non-whitelist chars.
 		$str = preg_replace('/[^a-zA-Z0-9\s\'\:\/\[\]-\pL]/u', '', $str);