1 files changed, 3 insertions, 1 deletions
diff --git a/packages/types/src/index.ts b/packages/types/src/index.ts
index 442fbb2d6..2e7e629b5 100644
--- a/packages/types/src/index.ts
+++ b/packages/types/src/index.ts
@@ -1,7 +1,9 @@
 import { BigNumber } from 'bignumber.js';
 
+export type JSONRPCErrorCallback = (err: Error | null, result?: JSONRPCResponsePayload) => void;
+
 export interface Provider {
-    sendAsync(payload: JSONRPCRequestPayload, callback: (err: Error, result: JSONRPCResponsePayload) => void): void;
+    sendAsync(payload: JSONRPCRequestPayload, callback: JSONRPCErrorCallback): void;
 }
 
 export type ContractAbi = AbiDefinition[];