diff --git a/data/api/client-server/sync.yaml b/data/api/client-server/sync.yaml
index 7d34353c..96680180 100644
--- a/data/api/client-server/sync.yaml
+++ b/data/api/client-server/sync.yaml
@@ -259,9 +259,10 @@ paths:
                                   {{% /boxes/note %}}
 
                                   If this field is set, even if it is empty, clients MUST
-                                  only update their local state with events in this list.
-                                  If this field is not set, clients MUST update their local
-                                  state with events in `state` and `timeline`.
+                                  only update their local state with events in this list,
+                                  and MUST NOT update their local state with events in
+                                  `timeline`. If this field is not set, clients MUST update
+                                  their local state with events in `state` and `timeline`.
 
                                   **Required** if `use_state_after` was set to `true` in the
                                   request, even if it is empty.
@@ -426,7 +427,8 @@ paths:
                                   The state updates for the room up to the **end** of the timeline.
 
                                   If this field is set, even if it is empty, clients MUST only
-                                  update their local state with events in this list. If this field
+                                  update their local state with events in this list, and MUST NOT
+                                  update their local state with events in `timeline`. If this field
                                   is not set, clients MUST update their local state with events in
                                   `state` and `timeline`.