diff --git a/lib/html2text.php b/lib/html2text.php
index b78b0ae1b9b..89c9e69bf72 100644
--- a/lib/html2text.php
+++ b/lib/html2text.php
@@ -580,9 +580,14 @@ class html2text
         }
 
         if (($index = array_search($url, $this->_link_list)) === false) {
+            // Add the link to the list.
             $this->_link_list[] = $url;
             $index = count($this->_link_list);
         }
+        else {
+            // Use the index of the existing link in the list (we enumerate from 1, not from 0).
+            $index++;
+        }
 
         return $display . ' [' . ($index) . ']';
     }