diff --git a/README.md b/README.md
index e34eed7..b32c00e 100644
--- a/README.md
+++ b/README.md
@@ -326,11 +326,9 @@ import { createRoute } from 'honox/factory'
 import { secureHeaders, NONCE } from 'hono/secure-headers'
 
 secureHeaders({
-  contentSecurityPolicy: import.meta.env.PROD
-    ? {
-        scriptSrc: [NONCE],
-      }
-    : undefined,
+  contentSecurityPolicy: {
+    scriptSrc: [NONCE]
+  }
 })
 ```