diff --git a/src/BaseServerWithMiddlewares.ts b/src/BaseServerWithMiddlewares.ts
index c143902..4c414fe 100644
--- a/src/BaseServerWithMiddlewares.ts
+++ b/src/BaseServerWithMiddlewares.ts
@@ -378,5 +378,5 @@ export type Middleware<RequestType> = (
     next: (
         req: RequestType,
         ctx: FakeRestContext,
-    ) => Promise<BaseResponse> | BaseResponse,
-) => Promise<BaseResponse> | BaseResponse | null | Promise<null>;
+    ) => Promise<BaseResponse | null> | BaseResponse | null,
+) => Promise<BaseResponse | null> | BaseResponse | null;