diff --git a/TableOfContents.php b/TableOfContents.php
index 1fc5f2c..68b1abc 100644
--- a/TableOfContents.php
+++ b/TableOfContents.php
@@ -222,7 +222,7 @@ private function getList($document, $headers, &$index = 0)
                 // Add missing id's to the h tags
                 $id = $curr_header->getAttribute('id');
                 if ($id === "") {
-                    $id = $this->slugify($curr_header->nodeValue);
+                    $id = $this->slugify($curr_header->nodeValue) . '-' . $index;
                     $curr_header->setAttribute('id', $id);
                 }