diff --git a/raw-body/index.d.ts b/raw-body/index.d.ts
index a99f2c51c2..94131c5764 100644
--- a/raw-body/index.d.ts
+++ b/raw-body/index.d.ts
@@ -4,13 +4,16 @@
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
 /// <reference types="node" />
+
 import { Readable } from "stream";
 
 declare namespace getRawBody {
+    export type Encoding = string | true;
+
     export interface Options {
         length?: number;
         limit?: number;
-        encoding?: string;
+        encoding?: Encoding;
     }
 
     export interface RawBodyError extends Error {
@@ -19,18 +22,18 @@ declare namespace getRawBody {
         expected?: number;
         received?: number;
         encoding?: string;
-        status?: number;
-        statusCode?: number;
-        type?: string;
+        status: number;
+        statusCode: number;
+        type: string;
     }
-
-    export type Callback = (err: RawBodyError, res: string | Buffer) => void;
 }
 
 
-declare function getRawBody(stream: Readable, callback: getRawBody.Callback): void;
-declare function getRawBody(stream: Readable, options: getRawBody.Options | string, callback: getRawBody.Callback): void;
+declare function getRawBody(stream: Readable, callback: (err: getRawBody.RawBodyError, body: Buffer) => void): void;
+declare function getRawBody(stream: Readable, options: (getRawBody.Options & { encoding: getRawBody.Encoding }) | getRawBody.Encoding, callback: (err: getRawBody.RawBodyError, body: string) => void): void;
+declare function getRawBody(stream: Readable, options: getRawBody.Options, callback: (err: getRawBody.RawBodyError, body: Buffer) => void): void;
 
-declare function getRawBody(stream: Readable, options?: getRawBody.Options | string): Promise<string | Buffer>;
+declare function getRawBody(stream: Readable, options: (getRawBody.Options & { encoding: getRawBody.Encoding }) | getRawBody.Encoding): Promise<string>;
+declare function getRawBody(stream: Readable, options?: getRawBody.Options): Promise<Buffer>;
 
 export = getRawBody;
diff --git a/raw-body/raw-body-tests.ts b/raw-body/raw-body-tests.ts
index f23160c876..ad6065537d 100644
--- a/raw-body/raw-body-tests.ts
+++ b/raw-body/raw-body-tests.ts
@@ -2,11 +2,11 @@ import getRawBody = require("raw-body");
 
 const stream: any = {};
 
-const simple = getRawBody(stream);
+const simple: Promise<Buffer> = getRawBody(stream);
 
-const withEncoding = getRawBody(stream, "utf-8");
+const withEncoding: Promise<string> = getRawBody(stream, "utf-8");
 
-const withOptions = getRawBody(stream, {
+const withOptions: Promise<string> = getRawBody(stream, {
     encoding: "utf-8",
     length: 1024,
     limit: 512