diff --git a/chainbase/src/main/java/org/tron/core/capsule/TransactionCapsule.java b/chainbase/src/main/java/org/tron/core/capsule/TransactionCapsule.java
index 95f436b19f0..8ac755ddea6 100755
--- a/chainbase/src/main/java/org/tron/core/capsule/TransactionCapsule.java
+++ b/chainbase/src/main/java/org/tron/core/capsule/TransactionCapsule.java
@@ -460,7 +460,7 @@ public static String getBase64FromByteString(ByteString sign) {
     byte[] s = sign.substring(32, 64).toByteArray();
     byte v = sign.byteAt(64);
     if (v < 27) {
-      v += 27; //revId -> v
+      v = (byte)(v + 27); //revId -> v
     }
     ECDSASignature signature = ECDSASignature.fromComponents(r, s, v);
     return signature.toBase64();