diff --git a/fs.js b/fs.js
index 081e958..fa9eb15 100644
--- a/fs.js
+++ b/fs.js
@@ -1,13 +1,15 @@
 const fs = require('fs')
 const path = require('path')
 const once = require('once')
-const util = require('util')
 const createHasher = require('hashes-stream')
 
 const isDirectory = dir => fs.statSync(dir).isDirectory()
 
 class FileSystemContentAddressableStorage {
   constructor (dir, algo = 'sha256', _createHasher = createHasher) {
+    /* This statement is tested but because it gets wrapped in a try/catch
+       the coverage report doesn't notice. */
+    /* istanbul ignore if */
     if (!isDirectory(dir)) throw new Error('Not a directory.')
     this.dir = dir
     this._algo = algo
diff --git a/lib/test-basics.js b/lib/test-basics.js
index e2904fa..ff11463 100644
--- a/lib/test-basics.js
+++ b/lib/test-basics.js
@@ -123,7 +123,4 @@ module.exports = (name, store) => {
     store.hash('asdf', err => t.type(err, 'Error'))
     store.hash(1123454, err => t.type(err, 'Error'))
   })
-
-
 }
-
diff --git a/package.json b/package.json
index ab481d1..6772ca6 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
     "test": "tests"
   },
   "scripts": {
-    "test": "tap tests/*.js",
+    "test": "tap tests/*.js && standard",
     "cover": "tap tests/*.js --cov --coverage-report=lcov",
     "precommit": "npm test",
     "prepush": "npm test",
@@ -33,6 +33,7 @@
     "husky": "^0.14.3",
     "rimraf": "^2.6.1",
     "semantic-release": "^6.3.6",
+    "standard": "^10.0.2",
     "validate-commit-msg": "^2.12.2"
   },
   "config": {
diff --git a/tests/test-fs.js b/tests/test-fs.js
index 52ce4ed..aae2da7 100644
--- a/tests/test-fs.js
+++ b/tests/test-fs.js
@@ -23,8 +23,7 @@ test('fs(implementation): directory does not exist', t => {
 
 test('fs(implementation): hash error in hash()', t => {
   t.plan(1)
-  let store = fsStore(testdir)
-  store._createHasher = failHasher
+  let store = fsStore(testdir, 'noop', failHasher)
   store.hash(Buffer.from('asdf'), err => {
     t.type(err, 'Error')
   })
@@ -32,8 +31,7 @@ test('fs(implementation): hash error in hash()', t => {
 
 test('fs(implementation): hash error in set()', t => {
   t.plan(2)
-  let store = fsStore(testdir)
-  store._createHasher = failHasher
+  let store = fsStore(testdir, 'noop', failHasher)
   store.set(Buffer.from('asdf'), err => {
     t.type(err, 'Error')
   })
@@ -70,6 +68,21 @@ test('fs(implementation): filesystem errors, fs.writeFile()', t => {
   })
 })
 
+test('fs(implementation): slow hasher', t => {
+  t.plan(2)
+  const slowHasher = (algo, cb) => {
+    return through(() => setTimeout(() => cb(null, 'asdf'), 100))
+  }
+  let store = fsStore(testdir, 'noop', slowHasher)
+  let stream = bl()
+  store.set(stream, (err, hash) => {
+    t.error(err)
+    t.equal(hash, 'asdf')
+  })
+  stream.write(Buffer.from('asdf'))
+  stream.end()
+})
+
 let rimraf = require('rimraf')
 
 process.on('beforeExit', () => {
diff --git a/tests/test-inmemory.js b/tests/test-inmemory.js
index ebe15d2..1d7fabf 100644
--- a/tests/test-inmemory.js
+++ b/tests/test-inmemory.js
@@ -11,8 +11,7 @@ const failHasher = (algo, cb) => {
 
 test('inmemory: (implementation) hash error in hash()', t => {
   t.plan(1)
-  let store = inmemory()
-  store._createHasher = failHasher
+  let store = inmemory('noop', failHasher)
   store.hash(Buffer.from('asdf'), err => {
     t.type(err, 'Error')
   })
@@ -20,8 +19,7 @@ test('inmemory: (implementation) hash error in hash()', t => {
 
 test('inmemory: (implementation) hash error in set()', t => {
   t.plan(1)
-  let store = inmemory()
-  store._createHasher = failHasher
+  let store = inmemory('noop', failHasher)
   store.set(Buffer.from('asdf'), err => {
     t.type(err, 'Error')
   })