diff --git a/lib/index.d.ts b/lib/index.d.ts
index 78b8745e..01dcce91 100644
--- a/lib/index.d.ts
+++ b/lib/index.d.ts
@@ -28,11 +28,11 @@ export type SessionOptions = {
 export type Handler = (req: any, res: any) => any;
 
 export type Session = {
-  set: <T = any>(name: string, value: T) => void;
+  set: <T = any>(name: string, value: T) => T;
   get: <T = any>(name: string) => T | undefined;
   unset: (name: string) => void;
   destroy: () => void;
-  save: () => Promise<void>;
+  save: () => Promise<string>;
 };
 
 export type CookieOptions = {