2 files changed, 16 insertions, 0 deletions
diff --git a/packages/subproviders/src/index.ts b/packages/subproviders/src/index.ts
index ff28b8a8d..6cc650a4d 100644
--- a/packages/subproviders/src/index.ts
+++ b/packages/subproviders/src/index.ts
@@ -4,6 +4,7 @@ export { ECSignature } from '@0xproject/types';
 
 import { LedgerEthereumClient } from './types';
 
+export { prependSubprovider } from './utils/subprovider_utils';
 export { EmptyWalletSubprovider } from './subproviders/empty_wallet_subprovider';
 export { FakeGasEstimateSubprovider } from './subproviders/fake_gas_estimate_subprovider';
 export { InjectedWeb3Subprovider } from './subproviders/injected_web3';
diff --git a/packages/subproviders/src/utils/subprovider_utils.ts b/packages/subproviders/src/utils/subprovider_utils.ts
new file mode 100644
index 000000000..24ebedd06
--- /dev/null
+++ b/packages/subproviders/src/utils/subprovider_utils.ts
@@ -0,0 +1,15 @@
+import ProviderEngine = require('web3-provider-engine');
+
+import { Subprovider } from '../subproviders/subprovider';
+
+/**
+ * Prepends a subprovider to a provider
+ * @param provider    Given provider
+ * @param subprovider Subprovider to prepend
+ */
+export function prependSubprovider(provider: ProviderEngine, subprovider: Subprovider): void {
+    subprovider.setEngine(provider);
+    // HACK: We use implementation details of provider engine here
+    // https://github.com/MetaMask/provider-engine/blob/master/index.js#L68
+    (provider as any)._providers = [subprovider, ...(provider as any)._providers];
+}