diff --git a/types/swagger-tools/index.d.ts b/types/swagger-tools/index.d.ts
index 340d962ba0..09d42138b6 100644
--- a/types/swagger-tools/index.d.ts
+++ b/types/swagger-tools/index.d.ts
@@ -58,7 +58,7 @@ export interface Middleware12 extends Middleware {
 }
 
 export interface Middleware20 extends Middleware {
-    swaggerUi(options: SwaggerUiOptions): NextHandleFunction;
+    swaggerUi(options?: SwaggerUiOptions): NextHandleFunction;
 }
 
 export type InitializeMiddlewareCallback12 = (middleware: Middleware12) => void;
diff --git a/types/swagger-tools/swagger-tools-tests.ts b/types/swagger-tools/swagger-tools-tests.ts
index e39670be7c..d4c695c418 100644
--- a/types/swagger-tools/swagger-tools-tests.ts
+++ b/types/swagger-tools/swagger-tools-tests.ts
@@ -36,6 +36,7 @@ swaggerTools.initializeMiddleware(swaggerDoc20, middleware => {
 
     // Serve the Swagger documents and Swagger UI
     app.use(middleware.swaggerUi(swaggerUiOptions));
+    app.use(middleware.swaggerUi());
 
     // Start the server
     createServer(app).listen(serverPort, () => {