diff --git a/optimade.rst b/optimade.rst
index 108a72a76..3dfb91d9c 100644
--- a/optimade.rst
+++ b/optimade.rst
@@ -599,6 +599,7 @@ Every response SHOULD contain the following fields, and MUST contain at least :f
              "issue_tracker": "http://tracker.example.com/exmpl-optimade"
            },
            "database": {
+               "id": "example_db",
              "name": "Example database 1 (of many)",
              "description": "The first example database in a series hosted by the Example Provider.",
              "homepage": "http://database_one.example.com",