diff --git a/source/includes/38_document.html.md b/source/includes/38_document.html.md
index 2ad610ad732..a696ab479e3 100644
--- a/source/includes/38_document.html.md
+++ b/source/includes/38_document.html.md
@@ -1,7 +1,7 @@
 ## Query an invoice document
 
 ```graphql
-query doc {
+query ($documentId: ID!) {
   document(id: $documentId) {
     date, 
     ... on InvoiceDocument {