diff --git a/package.json b/package.json
index 1e81b8e..4bc0887 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "fastify-http-proxy",
-  "version": "4.4.0",
+  "version": "5.0.0",
   "description": "proxy http requests, for Fastify",
   "main": "index.js",
   "scripts": {
diff --git a/test/ws-prefix-rewrite-core.js b/test/ws-prefix-rewrite-core.js
new file mode 100644
index 0000000..3aefb7e
--- /dev/null
+++ b/test/ws-prefix-rewrite-core.js
@@ -0,0 +1,146 @@
+'use strict'
+
+const t = require('tap')
+const { once } = require('events')
+
+const Fastify = require('fastify')
+const fastifyWebSocket = require('fastify-websocket')
+const proxy = require('..')
+const WebSocket = require('ws')
+const got = require('got')
+
+const level = 'warn'
+
+async function proxyServer (t, backendURL, backendPath, proxyOptions, wrapperOptions) {
+  const frontend = Fastify({ logger: { level } })
+  const registerProxy = async fastify => {
+    fastify.register(proxy, {
+      upstream: backendURL + backendPath,
+      http: true,
+      ...proxyOptions
+    })
+  }
+
+  t.comment('starting proxy to ' + backendURL + backendPath)
+
+  if (wrapperOptions) {
+    await frontend.register(registerProxy, wrapperOptions)
+  } else {
+    await registerProxy(frontend)
+  }
+
+  return [frontend, await frontend.listen(0)]
+}
+
+async function processRequest (t, frontendURL, path, expected) {
+  const url = new URL(path, frontendURL)
+  t.comment('ws connecting to ' + url.toString())
+  const ws = new WebSocket(url)
+  let wsResult, gotResult
+
+  try {
+    await once(ws, 'open')
+    t.pass('socket connected')
+
+    const [buf] = await Promise.race([once(ws, 'message'), once(ws, 'close')])
+    if (buf instanceof Buffer) {
+      wsResult = buf.toString()
+    } else {
+      t.comment('websocket closed')
+      wsResult = 'error'
+    }
+  } catch (e) {
+    wsResult = 'error'
+    ws.terminate()
+  }
+
+  try {
+    const result = await got(url)
+    gotResult = result.body
+  } catch (e) {
+    gotResult = 'error'
+  }
+
+  t.is(wsResult, expected)
+  t.is(gotResult, expected)
+}
+
+async function handleProxy (info, { backendPath, proxyOptions, wrapperOptions }, expected, ...paths) {
+  t.test(info, async function (t) {
+    const backend = Fastify({ logger: { level } })
+    await backend.register(fastifyWebSocket)
+
+    backend.get('/*', {
+      handler: (req, reply) => {
+        reply.send(req.url)
+      },
+      wsHandler: (conn, req) => {
+        conn.write(req.url)
+        conn.end()
+      }
+    })
+
+    t.teardown(() => backend.close())
+
+    const backendURL = await backend.listen(0)
+
+    const [frontend, frontendURL] = await proxyServer(t, backendURL, backendPath, proxyOptions, wrapperOptions)
+
+    t.teardown(() => frontend.close())
+
+    for (const path of paths) {
+      await processRequest(t, frontendURL, path, expected(path))
+    }
+
+    t.end()
+  })
+}
+
+handleProxy(
+  'no prefix to `/`',
+  {
+    backendPath: '/',
+    proxyOptions: { websocket: true }
+  },
+  path => path,
+  '/',
+  '/pub',
+  '/pub/'
+)
+
+handleProxy(
+  '`/pub/` to `/`',
+  {
+    backendPath: '/',
+    proxyOptions: { websocket: true, prefix: '/pub/' }
+  },
+  path => path.startsWith('/pub/') ? path.replace('/pub/', '/') : 'error',
+  '/',
+  '/pub/',
+  '/pub/test'
+)
+
+handleProxy(
+  '`/pub/` to `/public/`',
+  {
+    backendPath: '/public/',
+    proxyOptions: { websocket: true, prefix: '/pub/' }
+  },
+  path => path.startsWith('/pub/') ? path.replace('/pub/', '/public/') : 'error',
+  '/',
+  '/pub/',
+  '/pub/test'
+)
+
+handleProxy(
+  'wrapped `/pub/` to `/public/`',
+  {
+    backendPath: '/public/',
+    proxyOptions: { websocket: true },
+    wrapperOptions: { prefix: '/pub/' }
+  },
+  path => path.startsWith('/pub/') ? path.replace('/pub/', '/public/') : 'error',
+  '/',
+  '/pub/',
+  '/pub/test'
+)