diff --git a/examples/sztp/README.md b/examples/sztp/README.md
index f213e6a..6382925 100644
--- a/examples/sztp/README.md
+++ b/examples/sztp/README.md
@@ -111,6 +111,7 @@ $ jq . config/input.json
     "hw-model": "model-x",
     "os-name": "vendor-os",
     "os-version": "17.3R2.1",
+    "signed-data-preferred": [null],
     "nonce": "BASE64VALUE="
   }
 }
diff --git a/examples/sztp/config/input.json b/examples/sztp/config/input.json
index 1bdc36c..0236172 100644
--- a/examples/sztp/config/input.json
+++ b/examples/sztp/config/input.json
@@ -3,6 +3,7 @@
       "hw-model" : "model-x",
       "os-name" : "vendor-os",
       "os-version" : "17.3R2.1",
+      "signed-data-preferred": [null],
       "nonce" : "BASE64VALUE="
     }
   }
\ No newline at end of file