diff --git a/packages/zod-openapi/package.json b/packages/zod-openapi/package.json
index fd723ade..01cf2edf 100644
--- a/packages/zod-openapi/package.json
+++ b/packages/zod-openapi/package.json
@@ -40,7 +40,7 @@
   "homepage": "https://github.com/honojs/middleware",
   "peerDependencies": {
     "hono": ">=4.3.6",
-    "zod": "3.*"
+    "zod": "^3.25.0"
   },
   "devDependencies": {
     "@arethetypeswrong/cli": "^0.17.4",
@@ -49,10 +49,10 @@
     "typescript": "^5.8.2",
     "vitest": "^3.0.8",
     "yaml": "^2.4.3",
-    "zod": "^3.22.1"
+    "zod": "^3.25.0"
   },
   "dependencies": {
-    "@asteasolutions/zod-to-openapi": "^7.3.0",
+    "@asteasolutions/zod-to-openapi": "^8.0.0-beta.3",
     "@hono/zod-validator": "workspace:^"
   },
   "engines": {
diff --git a/packages/zod-openapi/src/index.test-d.ts b/packages/zod-openapi/src/index.test-d.ts
index e0127e9c..6e77c759 100644
--- a/packages/zod-openapi/src/index.test-d.ts
+++ b/packages/zod-openapi/src/index.test-d.ts
@@ -240,7 +240,7 @@ describe('coerce', () => {
     type Actual = ExtractSchema<typeof routes>['/api/users/:id']['$get']['input']
     type Expected = {
       param: {
-        id: number
+        id: unknown
       }
     }
     type verify = Expect<Equal<Expected, Actual>>
diff --git a/packages/zod-openapi/src/index.ts b/packages/zod-openapi/src/index.ts
index 217687ac..feb7f05a 100644
--- a/packages/zod-openapi/src/index.ts
+++ b/packages/zod-openapi/src/index.ts
@@ -11,6 +11,7 @@ import {
   OpenApiGeneratorV3,
   OpenApiGeneratorV31,
   extendZodWithOpenApi,
+  getOpenApiMetadata,
 } from '@asteasolutions/zod-to-openapi'
 import { zValidator } from '@hono/zod-validator'
 import { Hono } from 'hono'
@@ -36,8 +37,8 @@ import type {
 } from 'hono/utils/http-status'
 import type { JSONParsed, JSONValue, RemoveBlankRecord, SimplifyDeepArray } from 'hono/utils/types'
 import { mergePath } from 'hono/utils/url'
-import type { ZodError, ZodSchema } from 'zod'
-import { ZodType, z } from 'zod'
+import type { ZodError } from 'zod/v4'
+import { ZodType, z } from 'zod/v4'
 
 type MaybePromise<T> = Promise<T> | T
 
@@ -126,7 +127,7 @@ type InputTypeJson<R extends RouteConfig> = R['request'] extends RequestTypes
         ? {}
         : R['request']['body']['content'][keyof R['request']['body']['content']] extends Record<
               'schema',
-              ZodSchema<any>
+              ZodType<any>
             >
           ? {
               in: {
@@ -152,7 +153,7 @@ type InputTypeForm<R extends RouteConfig> = R['request'] extends RequestTypes
         ? {}
         : R['request']['body']['content'][keyof R['request']['body']['content']] extends Record<
               'schema',
-              ZodSchema<any>
+              ZodType<any>
             >
           ? {
               in: {
@@ -179,7 +180,7 @@ type InputTypeCookie<R extends RouteConfig> = InputTypeBase<R, 'cookies', 'cooki
 type ExtractContent<T> = T extends {
   [K in keyof T]: infer A
 }
-  ? A extends Record<'schema', ZodSchema>
+  ? A extends Record<'schema', ZodType>
     ? z.infer<A['schema']>
     : never
   : never
@@ -520,6 +521,7 @@ export class OpenAPIHono<
           }
         }
         if (isFormContentType(mediaType)) {
+          // @ts-expect-error The current zValidator does not accept ZodType
           const validator = zValidator('form', schema, hook as any)
           if (route.request?.body?.required) {
             validators.push(validator)
@@ -657,11 +659,14 @@ export class OpenAPIHono<
           })
 
         case 'schema':
-          return this.openAPIRegistry.register(def.schema._def.openapi._internal.refId, def.schema)
+          return this.openAPIRegistry.register(
+            getOpenApiMetadata(def.schema)._internal?.refId,
+            def.schema
+          )
 
         case 'parameter':
           return this.openAPIRegistry.registerParameter(
-            def.schema._def.openapi._internal.refId,
+            getOpenApiMetadata(def.schema)._internal?.refId,
             def.schema
           )
 
diff --git a/yarn.lock b/yarn.lock
index 8151bc69..41146555 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -99,14 +99,14 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@asteasolutions/zod-to-openapi@npm:^7.3.0":
-  version: 7.3.0
-  resolution: "@asteasolutions/zod-to-openapi@npm:7.3.0"
+"@asteasolutions/zod-to-openapi@npm:^8.0.0-beta.3":
+  version: 8.0.0-beta.3
+  resolution: "@asteasolutions/zod-to-openapi@npm:8.0.0-beta.3"
   dependencies:
     openapi3-ts: "npm:^4.1.2"
   peerDependencies:
-    zod: ^3.20.2
-  checksum: 10c0/f0a68a89929cdeaa3e21d2027489689f982824d676a9332c680e119f60881dd39b571324b24ad4837fda49bf6fe7c3e2af2199268b281bf1aec923d7a7cbfc40
+    zod: ~3.25.1
+  checksum: 10c0/73e9554ca4650bd7daa2cb4a66763e81e6d60a39c429db206e5c4bbd081ffbe6fac998b50a7b1e8ded4ca71b9629fafb8eadce4588d7fad89c1177869b2a35b7
   languageName: node
   linkType: hard
 
@@ -2379,17 +2379,17 @@ __metadata:
   resolution: "@hono/zod-openapi@workspace:packages/zod-openapi"
   dependencies:
     "@arethetypeswrong/cli": "npm:^0.17.4"
-    "@asteasolutions/zod-to-openapi": "npm:^7.3.0"
+    "@asteasolutions/zod-to-openapi": "npm:^8.0.0-beta.3"
     "@hono/zod-validator": "workspace:^"
     publint: "npm:^0.3.9"
     tsup: "npm:^8.4.0"
     typescript: "npm:^5.8.2"
     vitest: "npm:^3.0.8"
     yaml: "npm:^2.4.3"
-    zod: "npm:^3.22.1"
+    zod: "npm:^3.25.0"
   peerDependencies:
     hono: ">=4.3.6"
-    zod: 3.*
+    zod: ^3.25.0
   languageName: unknown
   linkType: soft
 
@@ -15153,7 +15153,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"zod@npm:^3.20.2, zod@npm:^3.22.1, zod@npm:^3.22.3":
+"zod@npm:^3.20.2, zod@npm:^3.22.3":
   version: 3.24.2
   resolution: "zod@npm:3.24.2"
   checksum: 10c0/c638c7220150847f13ad90635b3e7d0321b36cce36f3fc6050ed960689594c949c326dfe2c6fa87c14b126ee5d370ccdebd6efb304f41ef5557a4aaca2824565
@@ -15174,6 +15174,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"zod@npm:^3.25.0":
+  version: 3.25.64
+  resolution: "zod@npm:3.25.64"
+  checksum: 10c0/00d76093a999e377e4ffd037fa7185e861c35917e8c4272f514115c206a0654995168f57fb71708b11e0a9243206d988b7f63b543404e1796402e50d346a6bd7
+  languageName: node
+  linkType: hard
+
 "zod@npm:~3.25.6":
   version: 3.25.36
   resolution: "zod@npm:3.25.36"