diff --git a/specification/storage/data-plane/Microsoft.BlobStorage/preview/2019-12-12/blob.json b/specification/storage/data-plane/Microsoft.BlobStorage/preview/2019-12-12/blob.json
index 7e583aede637..f35d483681c9 100644
--- a/specification/storage/data-plane/Microsoft.BlobStorage/preview/2019-12-12/blob.json
+++ b/specification/storage/data-plane/Microsoft.BlobStorage/preview/2019-12-12/blob.json
@@ -8315,6 +8315,9 @@
           },
           {
             "$ref": "#/parameters/IfNoneMatch"
+          },
+          {
+            "$ref": "#/parameters/BlobConditionAppendPos"
           }
         ],
         "responses": {