diff --git a/x-pack/plugin/src/test/resources/rest-api-spec/api/slm.get_lifecycle.json b/x-pack/plugin/src/test/resources/rest-api-spec/api/slm.get_lifecycle.json
index 79d9cf5ece6bf..1413438d2ca1c 100644
--- a/x-pack/plugin/src/test/resources/rest-api-spec/api/slm.get_lifecycle.json
+++ b/x-pack/plugin/src/test/resources/rest-api-spec/api/slm.get_lifecycle.json
@@ -13,7 +13,7 @@
           ],
           "parts":{
             "policy_id":{
-              "type":"string",
+              "type":"list",
               "description":"Comma-separated list of snapshot lifecycle policies to retrieve"
             }
           }