diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..4a4833c
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,3 @@
+language: node_js
+node:
+  - lts/*
diff --git a/README.md b/README.md
index 05b3ce5..25ebaff 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,8 @@
 # random-access-chrome-file
 
+[![Build Status](https://travis-ci.com/random-access-storage/random-access-chrome-file.svg?branch=master)](https://travis-ci.com/random-access-storage/random-access-chrome-file)
+[![JavaScript Style Guide](https://img.shields.io/badge/code_style-standard-brightgreen.svg)](https://standardjs.com)
+
 A [random-access-storage](https://github.com/random-access-storage/random-access-storage) instance backed by the Chrome file system api
 
 ```
diff --git a/bench.js b/bench.js
index 88f29b6..7f4e401 100644
--- a/bench.js
+++ b/bench.js
@@ -37,7 +37,10 @@ function benchRead () {
   console.time('512mb read')
   st.read(0, 65536, function onread (err, buf) {
     if (err) throw err
-    if (offset >= 512 * 1024 * 1024) return console.timeEnd('512mb read')
+    if (offset >= 512 * 1024 * 1024) {
+      console.timeEnd('512mb read')
+      return process.exit(0) // we do this to close browser-runner
+    }
     st.read(offset += buf.length, 65536, onread)
   })
 }
diff --git a/browser-runner.config.js b/browser-runner.config.js
new file mode 100644
index 0000000..c15a2e8
--- /dev/null
+++ b/browser-runner.config.js
@@ -0,0 +1,17 @@
+const finished = require('tap-finished')
+
+let stream = null
+
+module.exports = {
+  beforeAll ({ shutdown }) {
+    stream = finished(function (results) {
+      if (results.ok) {
+        return shutdown(0)
+      }
+      shutdown(1)
+    })
+  },
+  onMessage (msg) {
+    stream.write(msg + '\n')
+  }
+}
diff --git a/index.js b/index.js
index 2763424..fadb037 100644
--- a/index.js
+++ b/index.js
@@ -1,4 +1,5 @@
 const ras = require('random-access-storage')
+const mutexify = require('mutexify')
 
 const TYPE = {type: 'octet/stream'}
 const requestFileSystem = window.requestFileSystem || window.webkitRequestFileSystem
@@ -29,6 +30,7 @@ function createFile (name, opts) {
 
   var fs = null
   var entry = null
+  var file = null
   var toDestroy = null
   var readers = []
   var writers = []
@@ -36,12 +38,12 @@ function createFile (name, opts) {
   return ras({read, write, open, stat, close, destroy})
 
   function read (req) {
-    const r = readers.pop() || new ReadRequest(readers, entry, mutex)
+    const r = readers.pop() || new ReadRequest(readers, entry, file, mutex)
     r.run(req)
   }
 
   function write (req) {
-    const w = writers.pop() || new WriteRequest(writers, entry, mutex)
+    const w = writers.pop() || new WriteRequest(writers, entry, file, mutex)
     w.run(req)
   }
 
@@ -51,9 +53,10 @@ function createFile (name, opts) {
   }
 
   function stat (req) {
-    entry.file(file => {
+    file.get((err, file) => {
+      if (err) return req.callback(err)
       req.callback(null, file)
-    }, err => req.callback(err))
+    })
   }
 
   function destroy (req) {
@@ -78,7 +81,11 @@ function createFile (name, opts) {
         mkdirp(parentFolder(name), function () {
           fs.root.getFile(name, {create: true}, function (e) {
             entry = toDestroy = e
-            req.callback(null)
+            file = new EntryFile(entry)
+            file.get((err) => {
+              if (err) return onerror(err)
+              req.callback(null)
+            })
           }, onerror)
         })
       }, onerror)
@@ -107,9 +114,10 @@ function parentFolder (path) {
   return /^\w:$/.test(p) ? '' : p
 }
 
-function WriteRequest (pool, entry, mutex) {
+function WriteRequest (pool, entry, file, mutex) {
   this.pool = pool
   this.entry = entry
+  this.file = file
   this.mutex = mutex
   this.writer = null
   this.req = null
@@ -122,8 +130,8 @@ WriteRequest.prototype.makeWriter = function () {
   this.entry.createWriter(function (writer) {
     self.writer = writer
 
-    writer.onwriteend = function () {
-      self.onwrite(null)
+    writer.onwriteend = function (e) {
+      self.onwrite(null, e)
     }
 
     writer.onerror = function (err) {
@@ -134,7 +142,7 @@ WriteRequest.prototype.makeWriter = function () {
   })
 }
 
-WriteRequest.prototype.onwrite = function (err) {
+WriteRequest.prototype.onwrite = function (err, e) {
   const req = this.req
   this.req = null
 
@@ -143,6 +151,10 @@ WriteRequest.prototype.onwrite = function (err) {
     this.mutex.release()
   }
 
+  if (!err) {
+    this.file.updateSize(e.currentTarget.length)
+  }
+
   if (this.truncating) {
     this.truncating = false
     if (!err) return this.run(req)
@@ -154,6 +166,7 @@ WriteRequest.prototype.onwrite = function (err) {
 
 WriteRequest.prototype.truncate = function () {
   this.truncating = true
+  this.file.truncate()
   this.writer.truncate(this.req.offset)
 }
 
@@ -164,7 +177,9 @@ WriteRequest.prototype.lock = function () {
 }
 
 WriteRequest.prototype.run = function (req) {
-  this.entry.file(file => {
+  this.file.getWritableFile((err, file) => {
+    if (err) return req.callback(err)
+
     this.req = req
     if (!this.writer || this.writer.length !== file.size) return this.makeWriter()
 
@@ -178,7 +193,7 @@ WriteRequest.prototype.run = function (req) {
 
     this.writer.seek(req.offset)
     this.writer.write(new Blob([req.data], TYPE))
-  }, err => req.callback(err))
+  })
 }
 
 function Mutex () {
@@ -202,9 +217,10 @@ Mutex.prototype.lock = function (req) {
   return true
 }
 
-function ReadRequest (pool, entry, mutex) {
+function ReadRequest (pool, entry, file, mutex) {
   this.pool = pool
   this.entry = entry
+  this.file = file
   this.mutex = mutex
   this.reader = new FileReader()
   this.req = null
@@ -233,8 +249,14 @@ ReadRequest.prototype.onread = function (err, buf) {
   const req = this.req
 
   if (err && this.retry) {
-    this.retry = false
-    if (this.lock(this)) this.run(req)
+    if (err.code !== 0) {
+      this.retry = false
+    }
+
+    if (this.lock(this)) {
+      this.file.clearFile()
+      this.run(req)
+    }
     return
   }
 
@@ -251,10 +273,69 @@ ReadRequest.prototype.onread = function (err, buf) {
 }
 
 ReadRequest.prototype.run = function (req) {
-  this.entry.file(file => {
+  this.file.get((err, file) => {
+    if (err) return req.callback(err)
+
     const end = req.offset + req.size
     this.req = req
     if (end > file.size) return this.onread(new Error('Could not satisfy length'), null)
     this.reader.readAsArrayBuffer(file.slice(req.offset, end))
-  }, err => req.callback(err))
+  })
+}
+
+class EntryFile {
+  constructor (entry) {
+    this._entry = entry
+    this._lock = mutexify()
+    this._file = null
+    this._size = 0
+    this._truncated = false
+  }
+
+  get size () {
+    return this._size
+  }
+
+  updateSize (size) {
+    if (!this._truncated && size > this._size) {
+      this._size = size
+    }
+
+    this.clearFile()
+  }
+
+  truncate () {
+    this._truncated = true
+  }
+
+  clearFile () {
+    this._file = null
+  }
+
+  get (cb) {
+    if (this._file && !this._truncated) {
+      return cb(null, this._file)
+    }
+
+    this._lock(release => {
+      if (this._file && !this._truncated) {
+        return release(cb, null, this._file)
+      }
+
+      this._entry.file(file => {
+        this._truncated = false
+        this._file = file
+        this._size = file.size
+        release(cb, null, file)
+      }, err => release(cb, err))
+    })
+  }
+
+  getWritableFile (cb) {
+    if (!this._truncated) {
+      return cb(null, this)
+    }
+
+    this.get(cb)
+  }
 }
diff --git a/package.json b/package.json
index 5f62f58..e95089d 100644
--- a/package.json
+++ b/package.json
@@ -4,13 +4,21 @@
   "description": "random-access-storage instance backed by the Chrome file system api.",
   "main": "index.js",
   "dependencies": {
+    "mutexify": "^1.3.0",
     "random-access-storage": "^1.3.0"
   },
   "devDependencies": {
-    "standard": "^11.0.1"
+    "@dxos/browser-runner": "^1.0.0-beta.9",
+    "random-access-test": "^1.0.0",
+    "standard": "^11.0.1",
+    "tap-finished": "0.0.1",
+    "tape": "^5.0.1"
   },
   "scripts": {
-    "test": "standard"
+    "test": "browser-runner test.js",
+    "posttest": "npm run lint",
+    "lint": "standard",
+    "bench": "browser-runner bench.js --timeout 0"
   },
   "repository": {
     "type": "git",
diff --git a/test.js b/test.js
new file mode 100644
index 0000000..1793044
--- /dev/null
+++ b/test.js
@@ -0,0 +1,67 @@
+const { promisify } = require('util')
+const test = require('tape')
+const randomAccessTest = require('random-access-test')
+const racf = require('./')
+
+const createStorage = (root) => (file, opts) => racf(`${root}/${file}`, opts)
+
+const storage = createStorage('tests-' + Math.random())
+
+randomAccessTest(function (name, options, callback) {
+  callback(storage(name, options))
+}, {})
+
+test('write/read concurrent requests', async t => {
+  const st = storage('random')
+
+  const rand = (min, max) => Math.floor(Math.random() * max) + min
+  const read = promisify(st.read.bind(st))
+  const write = promisify(st.write.bind(st))
+
+  try {
+    await new Promise(resolve => st.open(() => resolve()))
+
+    const buf = Buffer.alloc(1)
+
+    await Promise.all([...Array(1000).keys()].map(from => {
+      return write(from, buf)
+    }))
+
+    await Promise.all([...Array(1000).keys()].map(() => {
+      const row = rand(0, 2)
+      const from = rand(0, 1000)
+      const to = 1
+
+      if (row === 0) {
+        return read(from, to)
+      }
+      return write(from, buf)
+    }))
+
+    t.pass('should work ok with random concurrent request')
+    t.end()
+  } catch (err) {
+    t.end(err)
+  }
+})
+
+test('write concurrent requests over the same offset different size', async t => {
+  const st = storage('random')
+
+  const write = promisify(st.write.bind(st))
+
+  try {
+    await new Promise(resolve => st.open(() => resolve()))
+
+    await Promise.all([
+      write(0, Buffer.alloc(10)),
+      write(0, Buffer.alloc(1)),
+      write(0, Buffer.alloc(5))
+    ])
+
+    t.pass('should write multiple requests over the same offset different size')
+    t.end()
+  } catch (err) {
+    t.end(err)
+  }
+})