2 files changed, 5 insertions, 11 deletions
diff --git a/packages/migrations/src/utils/artifact_writer.ts b/packages/migrations/src/utils/artifact_writer.ts
index 2da5a09dd..b7522df05 100644
--- a/packages/migrations/src/utils/artifact_writer.ts
+++ b/packages/migrations/src/utils/artifact_writer.ts
@@ -4,8 +4,8 @@ import * as fs from 'fs';
 import * as path from 'path';
 
 export class ArtifactWriter {
-    private _artifactsDir: string;
-    private _networkId: number;
+    private readonly _artifactsDir: string;
+    private readonly _networkId: number;
     constructor(artifactsDir: string, networkId: number) {
         this._artifactsDir = artifactsDir;
         this._networkId = networkId;
diff --git a/packages/migrations/src/utils/provider_factory.ts b/packages/migrations/src/utils/provider_factory.ts
index 7a217b1e0..5f69b258d 100644
--- a/packages/migrations/src/utils/provider_factory.ts
+++ b/packages/migrations/src/utils/provider_factory.ts
@@ -1,10 +1,8 @@
-import { LedgerEthereumClient, LedgerSubprovider } from '@0xproject/subproviders';
+import { LedgerEthereumClient, LedgerSubprovider, RPCSubprovider, Web3ProviderEngine } from '@0xproject/subproviders';
 import Eth from '@ledgerhq/hw-app-eth';
 // tslint:disable:no-implicit-dependencies
 import TransportNodeHid from '@ledgerhq/hw-transport-node-hid';
 import { Provider } from 'ethereum-types';
-import ProviderEngine = require('web3-provider-engine');
-import RpcSubprovider = require('web3-provider-engine/subproviders/rpc');
 
 import { constants } from './constants';
 
@@ -15,18 +13,14 @@ async function ledgerEthereumNodeJsClientFactoryAsync(): Promise<LedgerEthereumC
 }
 export const providerFactory = {
     async getLedgerProviderAsync(): Promise<Provider> {
-        const provider = new ProviderEngine();
+        const provider = new Web3ProviderEngine();
         const ledgerWalletConfigs = {
             networkId: constants.KOVAN_NETWORK_ID,
             ledgerEthereumClientFactoryAsync: ledgerEthereumNodeJsClientFactoryAsync,
         };
         const ledgerSubprovider = new LedgerSubprovider(ledgerWalletConfigs);
         provider.addProvider(ledgerSubprovider);
-        provider.addProvider(
-            new RpcSubprovider({
-                rpcUrl: constants.RPC_URL,
-            }),
-        );
+        provider.addProvider(new RPCSubprovider(constants.RPC_URL));
         provider.start();
         return provider;
     },