diff --git a/challenge/index.ts b/challenge/index.ts
index e459cef..db3433a 100644
--- a/challenge/index.ts
+++ b/challenge/index.ts
@@ -42,9 +42,10 @@ const ptxn2 = algosdk.makePaymentTxnWithSuggestedParamsFromObject({
     amount: 2000000, // 2 ALGOs
 });
 
+const signer = algosdk.makeBasicAccountTransactionSigner(sender)
 const atc = new algosdk.AtomicTransactionComposer()
-atc.addTransaction({txn: ptxn1, signer: sender})
-atc.addTransaction({txn: ptxn2, signer: sender})
+atc.addTransaction({txn: ptxn1, signer: signer})
+atc.addTransaction({txn: ptxn2, signer: signer})
 
 const result = await algokit.sendAtomicTransactionComposer({atc:atc, sendParams: {suppressLog:true}}, algodClient)
 console.log(`The first payment transaction sent ${result.transactions[0].amount} microAlgos and the second payment transaction sent ${result.transactions[1].amount} microAlgos`)