diff --git a/cryptoCore/src/main/java/com/keystone/cold/cryptocore/RCCSigner.java b/cryptoCore/src/main/java/com/keystone/cold/cryptocore/RCCSigner.java
index aa802e37..7c8f362c 100644
--- a/cryptoCore/src/main/java/com/keystone/cold/cryptocore/RCCSigner.java
+++ b/cryptoCore/src/main/java/com/keystone/cold/cryptocore/RCCSigner.java
@@ -39,7 +39,7 @@ public String sign(String data, SignAlgo algo, int saltLen) {
             return null;
         }
         RCC rcc = new RCC();
-        String command = composeCommand(data, algo, saltLen, null);
+        String command = composeCommand(data, algo, saltLen, "");
 
         Log.e("Rust Signer:", command);