diff --git a/src/transaction.rs b/src/transaction.rs
index 4080d11be..0ccaf95a3 100644
--- a/src/transaction.rs
+++ b/src/transaction.rs
@@ -70,7 +70,7 @@ impl Transaction {
     }
 
     fn get_sign_data(&self) -> Vec<u8> {
-        serialize(&(&self.data)).unwrap()
+        serialize(&(&self.data)).expect("failed to serialize sign_data")
     }
 
     /// Sign this transaction.