diff --git a/express-jwt/express-jwt.d.ts b/express-jwt/express-jwt.d.ts
index 1aec6606fe..dadf833f67 100644
--- a/express-jwt/express-jwt.d.ts
+++ b/express-jwt/express-jwt.d.ts
@@ -12,21 +12,30 @@ declare module "express-jwt" {
 
     function jwt(options: jwt.Options): jwt.RequestHandler;
 
-    interface IDoneCallback<T> {
-        (err: Error, result: T): void;
-    }
-
-    type ICallback = <T>(req: express.Request, payload: T, done: IDoneCallback<boolean>) => void;
-
     namespace jwt {
+
+        export type secretType = string | Buffer
+        export interface SecretCallback {
+             (req: express.Request, header:any, payload: any, done: (err: any, secret?: boolean) => void): void;
+             (req: express.Request, payload: any, done: (err: any, secret?: secretType) => void):void;
+        }
+
+        export interface IsRevokedCallback {
+            (req: express.Request, payload: any, done: (err: any, revoked?: boolean) => void): void;
+        }
+
+        export interface GetTokenCallback {
+            (req: express.Request): any;
+        }
+
         export interface Options {
-            secret: string|Buffer|ICallback;
+            secret: secretType|SecretCallback;
             userProperty?: string;
             skip?: string[];
             credentialsRequired?: boolean;
-            isRevoked?: boolean;
+            isRevoked?: IsRevokedCallback;
             requestProperty?: string;
-            getToken?: ICallback;
+            getToken?: GetTokenCallback;
             [property: string]: any;
         }
         export interface RequestHandler extends express.RequestHandler {
@@ -34,4 +43,4 @@ declare module "express-jwt" {
         }
     }
     export = jwt;
-}
+}
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