diff --git a/api/server-server/definitions/unsigned_pdu.yaml b/api/server-server/definitions/unsigned_pdu.yaml
index 9e54a837..0aeede51 100644
--- a/api/server-server/definitions/unsigned_pdu.yaml
+++ b/api/server-server/definitions/unsigned_pdu.yaml
@@ -19,7 +19,7 @@ example:
 properties:
   event_id:
     type: string
-    description: The event ID for the PDU
+    description: The event ID for the PDU.
     example: "$a4ecee13e2accdadf56c1025:example.com"
   room_id:
     type: string