diff --git a/changelogs/client_server/newsfragments/3509.clarification b/changelogs/client_server/newsfragments/3509.clarification
new file mode 100644
index 00000000..3ccb2333
--- /dev/null
+++ b/changelogs/client_server/newsfragments/3509.clarification
@@ -0,0 +1 @@
+Fix various typos throughout the specification.
diff --git a/data/api/client-server/key_backup.yaml b/data/api/client-server/key_backup.yaml
index fcde550c..00ecdba6 100644
--- a/data/api/client-server/key_backup.yaml
+++ b/data/api/client-server/key_backup.yaml
@@ -878,6 +878,8 @@ paths:
                     }
                   }
                 }
+            required:
+              - rooms
         404:
           description: The backup was not found.
           examples: