diff --git a/data/api/client-server/definitions/olm_payload.yaml b/data/api/client-server/definitions/olm_payload.yaml
index 1d8e5055..8bac91e0 100644
--- a/data/api/client-server/definitions/olm_payload.yaml
+++ b/data/api/client-server/definitions/olm_payload.yaml
@@ -39,6 +39,7 @@ properties:
   sender_device_keys:
     $ref: device_keys.yaml 
     description: The sender's device keys.
+    x-addedInMatrixVersion: "1.15"
 required:
   - type
   - content