diff --git a/rest-api-spec/api/indices.segments.json b/rest-api-spec/api/indices.segments.json
index 95334be6b2f..caded349a6a 100644
--- a/rest-api-spec/api/indices.segments.json
+++ b/rest-api-spec/api/indices.segments.json
@@ -8,7 +8,6 @@
       "parts": {
         "index": {
           "type" : "list",
-          "required" : true,
           "description" : "A comma-separated list of index names; use `_all` or empty string to perform the operation on all indices"
         }
       },