diff --git a/specification/servicefabric/resource-manager/Microsoft.ServiceFabric/stable/2021-06-01/cluster.json b/specification/servicefabric/resource-manager/Microsoft.ServiceFabric/stable/2021-06-01/cluster.json
index d94c5efae642..9f42e02c32f8 100644
--- a/specification/servicefabric/resource-manager/Microsoft.ServiceFabric/stable/2021-06-01/cluster.json
+++ b/specification/servicefabric/resource-manager/Microsoft.ServiceFabric/stable/2021-06-01/cluster.json
@@ -1969,6 +1969,10 @@
         "Windows",
         "Linux"
       ],
+      "x-ms-enum": {
+        "name": "ClusterVersionsEnvironment",
+        "modelAsString": true
+      },
       "x-ms-parameter-location": "method"
     },
     "locationForClusterCodeVersions": {