diff --git a/spec/schemas/_common.yaml b/spec/schemas/_common.yaml
index bf1f45525..31eabcc95 100644
--- a/spec/schemas/_common.yaml
+++ b/spec/schemas/_common.yaml
@@ -322,22 +322,22 @@ components:
     ShardFailure:
       type: object
       properties:
-        index:
+        _index:
           $ref: '#/components/schemas/IndexName'
-        node:
+        _node:
           type: string
         reason:
           $ref: '#/components/schemas/ErrorCause'
-        shard:
+        _shard:
           type: integer
         status:
           type: string
         primary:
           type: boolean
       required:
+        - _shard
         - primary
         - reason
-        - shard
     ShardSearchFailure:
       type: object
       description: Represents a failure to search on a specific shard. Used in search responses.