diff --git a/js/tables.js b/js/tables.js
index bce0463..136771c 100644
--- a/js/tables.js
+++ b/js/tables.js
@@ -59,12 +59,13 @@ function tables_sort(element, column, direction, type){
     }
 
     const rows = Array.from(tbody.children);
-    const header = rows[0].classList.contains('header');
-    const header_row = header ? rows.shift() : '';
     if(rows.length === 0){
         return;
     }
 
+    const header = rows[0].classList.contains('header');
+    const header_row = header ? rows.shift() : '';
+
     const column_content = [];
     let main_column = 0;
     for(const cssClass of table.classList){