1 files changed, 4 insertions, 5 deletions
diff --git a/packages/contracts/src/utils/transaction_factory.ts b/packages/contracts/src/utils/transaction_factory.ts
index 941bff96d..65cdb3f89 100644
--- a/packages/contracts/src/utils/transaction_factory.ts
+++ b/packages/contracts/src/utils/transaction_factory.ts
@@ -7,26 +7,25 @@ import { signingUtils } from './signing_utils';
 import { SignatureType, SignedTransaction } from './types';
 
 export class TransactionFactory {
-    private _signer: string;
+    private _signerBuff: Buffer;
     private _exchangeAddress: string;
     private _privateKey: Buffer;
     constructor(privateKey: Buffer, exchangeAddress: string) {
         this._privateKey = privateKey;
         this._exchangeAddress = exchangeAddress;
-        const signerBuff = ethUtil.privateToAddress(this._privateKey);
-        this._signer = `0x${signerBuff.toString('hex')}`;
+        this._signerBuff = ethUtil.privateToAddress(this._privateKey);
     }
     public newSignedTransaction(
         data: string,
         signatureType: SignatureType = SignatureType.Ecrecover,
     ): SignedTransaction {
         const salt = generatePseudoRandomSalt();
-        const txHash = crypto.solSHA3([this._exchangeAddress, salt, ethUtil.toBuffer(data)]);
+        const txHash = crypto.solSHA3([this._exchangeAddress, this._signerBuff, salt, ethUtil.toBuffer(data)]);
         const signature = signingUtils.signMessage(txHash, this._privateKey, signatureType);
         const signedTx = {
             exchangeAddress: this._exchangeAddress,
             salt,
-            signer: this._signer,
+            signer: `0x${this._signerBuff.toString('hex')}`,
             data,
             signature: `0x${signature.toString('hex')}`,
         };