diff --git a/teos-common/src/test_utils.rs b/teos-common/src/test_utils.rs
index dd0a3336..79e21206 100644
--- a/teos-common/src/test_utils.rs
+++ b/teos-common/src/test_utils.rs
@@ -5,10 +5,9 @@ use rand::distributions::Standard;
 use rand::prelude::Distribution;
 use rand::Rng;
 
-use bitcoin::consensus;
 use bitcoin::hashes::Hash;
 use bitcoin::secp256k1::SecretKey;
-use bitcoin::Txid;
+use bitcoin::{consensus, Script, Transaction, TxOut, Txid};
 
 use crate::appointment::{Appointment, Locator};
 use crate::cryptography;
@@ -48,7 +47,15 @@ pub fn generate_random_appointment(dispute_txid: Option<&Txid>) -> Appointment {
     };
 
     let tx_bytes = Vec::from_hex(TX_HEX).unwrap();
-    let penalty_tx = consensus::deserialize(&tx_bytes).unwrap();
+    let mut penalty_tx: Transaction = consensus::deserialize(&tx_bytes).unwrap();
+
+    // Append a random-sized OP_RETURN to make each transcation random in size.
+    penalty_tx.output.push(TxOut {
+        value: 0,
+        script_pubkey: Script::new_op_return(&cryptography::get_random_bytes(
+            rand::thread_rng().gen_range(1..=80),
+        )),
+    });
 
     let mut raw_locator: [u8; 16] = cryptography::get_random_bytes(16).try_into().unwrap();
     raw_locator.copy_from_slice(&dispute_txid[..16]);