diff --git a/src/ColumnSortable/SortableLink.php b/src/ColumnSortable/SortableLink.php
index 986b0f2..8499acb 100644
--- a/src/ColumnSortable/SortableLink.php
+++ b/src/ColumnSortable/SortableLink.php
@@ -248,7 +248,7 @@ private static function shouldShowActive($sortColumn)
     private static function buildQueryString($queryParameters, $sortParameter, $direction)
     {
         $checkStrlenOrArray = function ($element) {
-            return is_array($element) ? $element : strlen($element);
+            return is_array($element) ? $element : strlen($element ?? '');
         };
 
         $persistParameters = array_filter(request()->except('sort', 'direction', 'page'), $checkStrlenOrArray);