diff --git a/specification/storage/resource-manager/Microsoft.Storage/stable/2019-06-01/file.json b/specification/storage/resource-manager/Microsoft.Storage/stable/2019-06-01/file.json
index bba100994b25..9e603d1881fa 100644
--- a/specification/storage/resource-manager/Microsoft.Storage/stable/2019-06-01/file.json
+++ b/specification/storage/resource-manager/Microsoft.Storage/stable/2019-06-01/file.json
@@ -709,6 +709,7 @@
         },
         "shareUsageBytes": {
           "type": "integer",
+          "format": "int64",
           "readOnly": true,
           "description": "The approximate size of the data stored on the share. Note that this value may not include all recently created or recently resized files."
         }