diff --git a/examples/fastify/zod/fetch.ts b/examples/fastify/zod/fetch.ts
index 0a11079..36cca01 100644
--- a/examples/fastify/zod/fetch.ts
+++ b/examples/fastify/zod/fetch.ts
@@ -50,6 +50,10 @@ const main = async () => {
       const r = await res.json();
       console.log(`${path}:${method} => ${r.userId}`);
       console.log(res.headers.get("Content-Type"));
+      // eslint-disable-next-line @typescript-eslint/no-unused-vars
+      const contentType: "application/json" = res.headers.get("Content-Type");
+      // eslint-disable-next-line @typescript-eslint/no-unused-vars
+      const hasContentType: true = res.headers.has("Content-Type");
     } else {
       // e is the response schema defined in pathMap["/users"]["post"].res other than "20X"
       const e = await res.text();
diff --git a/examples/spec/zod.ts b/examples/spec/zod.ts
index 00a41fa..cf4265f 100644
--- a/examples/spec/zod.ts
+++ b/examples/spec/zod.ts
@@ -2,8 +2,8 @@ import { z } from "zod";
 import { ToApiEndpoints, ZodApiEndpoints } from "../../src";
 
 const JsonHeader = z.union([
-  z.object({ "content-type": z.string() }),
-  z.object({ "Content-Type": z.string() }),
+  z.object({ "content-type": z.literal("application/json") }),
+  z.object({ "Content-Type": z.literal("application/json") }),
 ]);
 export const pathMap = {
   "/users": {