diff --git a/lib/server.js b/lib/server.js
index a8946e1..a73107e 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -5,11 +5,29 @@
  */
 import Reader from './reader.js'
 
+/** @import { FastifyPluginCallback, FastifyReply } from 'fastify' */
+/** @import { Resource } from './reader.js' */
+
+/**
+ * @param {FastifyReply} reply
+ * @param {Resource} resource
+ * @returns {FastifyReply} reply
+ */
+function sendResource(reply, resource) {
+  reply
+    .type(resource.contentType)
+    .header('content-length', resource.contentLength)
+  if (resource.contentEncoding) {
+    reply.header('content-encoding', resource.contentEncoding)
+  }
+  return reply.send(resource.stream)
+}
+
 /**
  * Fastify plugin for serving a styled map package. User `lazy: true` to defer
  * opening the file until the first request.
  *
- * @type {import("fastify").FastifyPluginCallback<PluginOptions>}
+ * @type {FastifyPluginCallback<PluginOptions>}
  */
 export default function (fastify, { filepath, lazy = false }, done) {
   /** @type {Reader | undefined} */
@@ -17,42 +35,30 @@ export default function (fastify, { filepath, lazy = false }, done) {
   if (!lazy) {
     reader = new Reader(filepath)
   }
-  const fd = fastify.decorateReply(
-    'sendResource',
-    /** @param {import('./reader.js').Resource} resource */
-    function (resource) {
-      this.type(resource.contentType).header(
-        'content-length',
-        resource.contentLength,
-      )
-      if (resource.contentEncoding)
-        this.header('content-encoding', resource.contentEncoding)
-      // @ts-ignore
-      return this.send(resource.stream)
-    },
-  )
 
-  fd.get('/style.json', async (request, reply) => {
+  fastify.get('/style.json', async (_request, reply) => {
     if (!reader) {
       reader = new Reader(filepath)
     }
-    // @ts-ignore - can't type this and keep it encapsulated
-    return reply.sendResource(await reader.getStyle(fastify.listeningOrigin))
+    return sendResource(reply, await reader.getStyle(fastify.listeningOrigin))
   })
-  fd.get('*', async (request, reply) => {
+
+  fastify.get('*', async (request, reply) => {
     if (!reader) {
       reader = new Reader(filepath)
     }
+
+    /** @type {Resource} */
+    let resource
     try {
-      // @ts-ignore - can't type this and keep it encapsulated
-      return reply.sendResource(
-        await reader.getResource(decodeURI(request.url)),
-      )
+      resource = await reader.getResource(decodeURI(request.url))
     } catch (e) {
       // @ts-ignore
       e.statusCode = 404
       throw e
     }
+
+    return sendResource(reply, resource)
   })
   done()
 }