diff --git a/perf-measures/type-check/client.ts b/perf-measures/type-check/client.ts
index 022a5bef..289ede0c 100644
--- a/perf-measures/type-check/client.ts
+++ b/perf-measures/type-check/client.ts
@@ -1,4 +1,4 @@
-import type { app } from './generated/app'
 import { hc } from '../../src/client'
+import type { app } from './generated/app'
 
 const client = hc<typeof app>('/')
diff --git a/src/client/types.ts b/src/client/types.ts
index e64a98eb..7a345370 100644
--- a/src/client/types.ts
+++ b/src/client/types.ts
@@ -1,4 +1,5 @@
 import type { Hono } from '../hono'
+import type { HonoBase } from '../hono-base'
 import type { Endpoint, ResponseFormat, Schema } from '../types'
 import type { StatusCode, SuccessStatusCode } from '../utils/http-status'
 import type { HasRequiredKeys } from '../utils/types'
@@ -159,7 +160,7 @@ type PathToChain<
     }
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
-export type Client<T> = T extends Hono<any, infer S, any>
+export type Client<T> = T extends HonoBase<any, infer S, any>
   ? S extends Record<infer K, Schema>
     ? K extends string
       ? PathToChain<K, S>
diff --git a/src/hono-base.ts b/src/hono-base.ts
index 9597a33b..a10f28b6 100644
--- a/src/hono-base.ts
+++ b/src/hono-base.ts
@@ -26,7 +26,6 @@ import type {
   RouterRoute,
   Schema,
 } from './types'
-import type { ExcludeEmptyObject } from './utils/types'
 import { getPath, getPathNoStrict, mergePath } from './utils/url'
 
 /**
@@ -213,11 +212,7 @@ class Hono<E extends Env = Env, S extends Schema = {}, BasePath extends string =
   >(
     path: SubPath,
     app: Hono<SubEnv, SubSchema, SubBasePath>
-  ): Hono<
-    E,
-    ExcludeEmptyObject<MergeSchemaPath<SubSchema, MergePath<BasePath, SubPath>> | S>,
-    BasePath
-  > {
+  ): Hono<E, MergeSchemaPath<SubSchema, MergePath<BasePath, SubPath>> | S, BasePath> {
     const subApp = this.basePath(path)
     app.routes.map((r) => {
       let handler
diff --git a/src/utils/types.ts b/src/utils/types.ts
index 4a9647e3..0c124785 100644
--- a/src/utils/types.ts
+++ b/src/utils/types.ts
@@ -97,5 +97,3 @@ export type IsAny<T> = boolean extends (T extends never ? true : false) ? true :
  * @see https://github.com/Microsoft/TypeScript/issues/29729
  */
 export type StringLiteralUnion<T> = T | (string & Record<never, never>)
-
-export type ExcludeEmptyObject<T> = T extends {} ? ({} extends T ? never : T) : T