diff --git a/contracts/exchange/test/dispatcher.ts b/contracts/exchange/test/dispatcher.ts
index 7d36aca270..fdddc21e95 100644
--- a/contracts/exchange/test/dispatcher.ts
+++ b/contracts/exchange/test/dispatcher.ts
@@ -290,7 +290,7 @@ describe('AssetProxyDispatcher', () => {
             const expectedError = new ExchangeRevertErrors.AssetProxyTransferError(
                 orderHash,
                 encodedAssetData,
-                nestedError.toString(),
+                nestedError.encode(),
             );
             const tx = assetProxyDispatcher
                 .dispatchTransferFrom(orderHash, encodedAssetData, makerAddress, takerAddress, amount)
@@ -313,7 +313,7 @@ describe('AssetProxyDispatcher', () => {
             const expectedError = new ExchangeRevertErrors.AssetProxyTransferError(
                 transferIndexAsBytes32,
                 assetDataB,
-                nestedError.toString(),
+                nestedError.encode(),
             );
             const tx = assetProxyDispatcher
                 .simulateDispatchTransferFromCalls(
diff --git a/contracts/exchange/test/signature_validator.ts b/contracts/exchange/test/signature_validator.ts
index 8dce19f20c..07d66760d2 100644
--- a/contracts/exchange/test/signature_validator.ts
+++ b/contracts/exchange/test/signature_validator.ts
@@ -300,7 +300,7 @@ blockchainTests.resets('MixinSignatureValidator', env => {
                 hashHex,
                 validatorWallet.address,
                 signatureHex,
-                new StringRevertError(validatorWalletRevertReason).toString(),
+                new StringRevertError(validatorWalletRevertReason).encode(),
             );
             const tx = validateAsync(hashHex, validatorWallet.address, signatureHex, ValidatorWalletAction.Revert);
             return expect(tx).to.revertWith(expectedError);
@@ -562,7 +562,7 @@ blockchainTests.resets('MixinSignatureValidator', env => {
                 validatorWallet.address,
                 data,
                 signatureHex,
-                new StringRevertError(validatorWalletRevertReason).toString(),
+                new StringRevertError(validatorWalletRevertReason).encode(),
             );
             const tx = validateAsync(signedOrder, signatureHex, ValidatorWalletAction.Revert);
             return expect(tx).to.revertWith(expectedError);
@@ -693,7 +693,7 @@ blockchainTests.resets('MixinSignatureValidator', env => {
                 validatorWallet.address,
                 data,
                 signatureHex,
-                new StringRevertError(validatorWalletRevertReason).toString(),
+                new StringRevertError(validatorWalletRevertReason).encode(),
             );
             const tx = validateAsync(signedOrder, signatureHex, ValidatorWalletAction.Revert);
             return expect(tx).to.revertWith(expectedError);
@@ -916,7 +916,7 @@ blockchainTests.resets('MixinSignatureValidator', env => {
                 validatorWallet.address,
                 data,
                 signatureHex,
-                new StringRevertError(validatorWalletRevertReason).toString(),
+                new StringRevertError(validatorWalletRevertReason).encode(),
             );
             const tx = validateAsync(signedTransaction, signatureHex, ValidatorWalletAction.Revert);
             return expect(tx).to.revertWith(expectedError);
@@ -1041,7 +1041,7 @@ blockchainTests.resets('MixinSignatureValidator', env => {
                 validatorWallet.address,
                 data,
                 signatureHex,
-                new StringRevertError(validatorWalletRevertReason).toString(),
+                new StringRevertError(validatorWalletRevertReason).encode(),
             );
             const tx = validateAsync(signedTransaction, signatureHex, ValidatorWalletAction.Revert);
             return expect(tx).to.revertWith(expectedError);
diff --git a/contracts/exchange/test/transactions_unit_tests.ts b/contracts/exchange/test/transactions_unit_tests.ts
index 318e9c472d..a237bf3853 100644
--- a/contracts/exchange/test/transactions_unit_tests.ts
+++ b/contracts/exchange/test/transactions_unit_tests.ts
@@ -101,7 +101,7 @@ blockchainTests.resets('Transaction Unit Tests', ({ provider, web3Wrapper, txDef
             const executableError = new StringRevertError('EXECUTABLE_FAILED');
             const expectedError = new ExchangeRevertErrors.TransactionExecutionError(
                 transactionHash,
-                executableError.toString(),
+                executableError.encode(),
             );
 
             // Call the `batchExecuteTransactions()` function and ensure that it reverts with the expected revert error.
@@ -123,7 +123,7 @@ blockchainTests.resets('Transaction Unit Tests', ({ provider, web3Wrapper, txDef
             const executableError = new StringRevertError('EXECUTABLE_FAILED');
             const expectedError = new ExchangeRevertErrors.TransactionExecutionError(
                 transactionHash,
-                executableError.toString(),
+                executableError.encode(),
             );
 
             // Call the `batchExecuteTransactions()` function and ensure that it reverts with the expected revert error.
@@ -145,7 +145,7 @@ blockchainTests.resets('Transaction Unit Tests', ({ provider, web3Wrapper, txDef
             const executableError = new StringRevertError('EXECUTABLE_FAILED');
             const expectedError = new ExchangeRevertErrors.TransactionExecutionError(
                 transactionHash,
-                executableError.toString(),
+                executableError.encode(),
             );
 
             // Call the `batchExecuteTransactions()` function and ensure that it reverts with the expected revert error.
@@ -280,7 +280,7 @@ blockchainTests.resets('Transaction Unit Tests', ({ provider, web3Wrapper, txDef
             const outerExecuteTransactionHash = transactionHashUtils.getTransactionHashHex(outerExecuteTransaction);
             const outerExpectedError = new ExchangeRevertErrors.TransactionExecutionError(
                 outerExecuteTransactionHash,
-                innerExpectedError.toString(),
+                innerExpectedError.encode(),
             );
             const tx = transactionsContract
                 .batchExecuteTransactions([outerExecuteTransaction], [randomSignature()])
@@ -363,7 +363,7 @@ blockchainTests.resets('Transaction Unit Tests', ({ provider, web3Wrapper, txDef
             const errorData = new ExchangeRevertErrors.TransactionInvalidContextError(
                 innerTransactionHash,
                 accounts[0],
-            ).toString();
+            ).encode();
             const expectedError = new ExchangeRevertErrors.TransactionExecutionError(outerTransactionHash, errorData);
             const tx = transactionsContract
                 .executeTransaction(outerTransaction, validSignature)
@@ -385,7 +385,7 @@ blockchainTests.resets('Transaction Unit Tests', ({ provider, web3Wrapper, txDef
             const errorData = new ExchangeRevertErrors.TransactionInvalidContextError(
                 innerTransactionHash,
                 accounts[0],
-            ).toString();
+            ).encode();
             const expectedError = new ExchangeRevertErrors.TransactionExecutionError(outerTransactionHash, errorData);
             const tx = transactionsContract
                 .executeTransaction(outerTransaction, validSignature)
@@ -466,7 +466,7 @@ blockchainTests.resets('Transaction Unit Tests', ({ provider, web3Wrapper, txDef
             const executableError = new StringRevertError('EXECUTABLE_FAILED');
             const expectedError = new ExchangeRevertErrors.TransactionExecutionError(
                 transactionHash,
-                executableError.toString(),
+                executableError.encode(),
             );
             const tx = transactionsContract
                 .executeTransaction(transaction, randomSignature())
@@ -486,7 +486,7 @@ blockchainTests.resets('Transaction Unit Tests', ({ provider, web3Wrapper, txDef
             const executableError = new StringRevertError('EXECUTABLE_FAILED');
             const expectedError = new ExchangeRevertErrors.TransactionExecutionError(
                 transactionHash,
-                executableError.toString(),
+                executableError.encode(),
             );
             const tx = transactionsContract
                 .executeTransaction(transaction, validSignature)