diff --git a/integrationTest/helpers.ts b/integrationTest/helpers.ts
index 5e653ea222..417cf63bef 100644
--- a/integrationTest/helpers.ts
+++ b/integrationTest/helpers.ts
@@ -1,12 +1,12 @@
 import * as path from 'path';
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import { expect } from 'chai';
 import { ScoreResult } from 'stryker-api/report';
 
 export async function readScoreResult(eventResultDirectory = path.resolve('reports', 'mutation', 'events')) {
-    const allReportFiles = await fs.readdir(eventResultDirectory);
+    const allReportFiles = await fsAsPromised.readdir(eventResultDirectory);
     const scoreResultReportFile = allReportFiles.find(file => !!file.match(/.*onScoreCalculated.*/));
     expect(scoreResultReportFile).ok;
-    const scoreResultContent = await fs.readFile(path.resolve(eventResultDirectory, scoreResultReportFile || ''), 'utf8');
+    const scoreResultContent = await fsAsPromised.readFile(path.resolve(eventResultDirectory, scoreResultReportFile || ''), 'utf8');
     return JSON.parse(scoreResultContent) as ScoreResult;
 }
diff --git a/integrationTest/package.json b/integrationTest/package.json
index 96a036979d..1115bfc08d 100644
--- a/integrationTest/package.json
+++ b/integrationTest/package.json
@@ -20,7 +20,6 @@
     "link-parent-bin": "~0.2.0",
     "load-grunt-tasks": "~4.0.0",
     "mocha": "~5.2.0",
-    "mz": "~2.7.0",
     "ts-node": "~7.0.0",
     "typescript": "~2.9.2",
     "webpack": "~4.16.0"
@@ -41,6 +40,7 @@
     "stryker-karma-runner": "../packages/stryker-karma-runner",
     "stryker-mocha-framework": "../packages/stryker-mocha-framework",
     "stryker-mocha-runner": "../packages/stryker-mocha-runner",
+    "@stryker-mutator/util": "../packages/stryker-util",
     "stryker-typescript": "../packages/stryker-typescript",
     "stryker-vue-mutator": "../packages/stryker-vue-mutator",
     "stryker-webpack-transpiler": "../packages/stryker-webpack-transpiler"
diff --git a/integrationTest/test/angular-project/package-lock.json b/integrationTest/test/angular-project/package-lock.json
index ebbe84f822..5c88b6e738 100644
--- a/integrationTest/test/angular-project/package-lock.json
+++ b/integrationTest/test/angular-project/package-lock.json
@@ -431,12 +431,6 @@
         "@types/jasmine": "*"
       }
     },
-    "@types/node": {
-      "version": "8.9.5",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-8.9.5.tgz",
-      "integrity": "sha512-jRHfWsvyMtXdbhnz5CVHxaBgnV6duZnPlQuRSo/dm/GnmikNcmZhxIES4E9OZjUmQ8C+HCl4KJux+cXN/ErGDQ==",
-      "dev": true
-    },
     "@types/q": {
       "version": "0.0.32",
       "resolved": "https://registry.npmjs.org/@types/q/-/q-0.0.32.tgz",
diff --git a/integrationTest/test/angular-project/package.json b/integrationTest/test/angular-project/package.json
index 06c146281b..3969dec97c 100644
--- a/integrationTest/test/angular-project/package.json
+++ b/integrationTest/test/angular-project/package.json
@@ -34,7 +34,6 @@
     "@angular/language-service": "^6.0.3",
     "@types/jasmine": "~2.8.6",
     "@types/jasminewd2": "~2.0.3",
-    "@types/node": "~8.9.4",
     "codelyzer": "~4.2.1",
     "jasmine-core": "~2.99.1",
     "jasmine-spec-reporter": "~4.2.1",
@@ -51,6 +50,7 @@
   "localDependencies": {
     "stryker": "../../../packages/stryker",
     "stryker-karma-runner": "../../../packages/stryker-karma-runner",
-    "stryker-typescript": "../../../packages/stryker-typescript"
+    "stryker-typescript": "../../../packages/stryker-typescript",
+    "@stryker-mutator/util": "../../../packages/stryker-util"
   }
 }
diff --git a/integrationTest/test/angular-project/verify/verify.ts b/integrationTest/test/angular-project/verify/verify.ts
index 0ade81dc18..f522d0a181 100644
--- a/integrationTest/test/angular-project/verify/verify.ts
+++ b/integrationTest/test/angular-project/verify/verify.ts
@@ -1,4 +1,4 @@
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import { expect } from 'chai';
 import * as path from 'path';
 import { ScoreResult } from 'stryker-api/report';
@@ -6,10 +6,10 @@ import { ScoreResult } from 'stryker-api/report';
 describe('After running stryker on angular project', () => {
   it('should report 15% mutation score', async () => {
     const eventsDir = path.resolve(__dirname, '..', 'reports', 'mutation', 'events');
-    const allReportFiles = await fs.readdir(eventsDir);
+    const allReportFiles = await fsAsPromised.readdir(eventsDir);
     const scoreResultReportFile = allReportFiles.find(file => !!file.match(/.*onScoreCalculated.*/));
     expect(scoreResultReportFile).ok;
-    const scoreResultContent = await fs.readFile(path.resolve(eventsDir, scoreResultReportFile || ''), 'utf8');
+    const scoreResultContent = await fsAsPromised.readFile(path.resolve(eventsDir, scoreResultReportFile || ''), 'utf8');
     const scoreResult = JSON.parse(scoreResultContent) as ScoreResult;
     expect(scoreResult.killed).eq(2);
     expect(scoreResult.survived).eq(11);
diff --git a/integrationTest/test/babel-transpiling/verify/verify.ts b/integrationTest/test/babel-transpiling/verify/verify.ts
index 59d5c652d6..60cd78a858 100644
--- a/integrationTest/test/babel-transpiling/verify/verify.ts
+++ b/integrationTest/test/babel-transpiling/verify/verify.ts
@@ -1,9 +1,9 @@
 import * as chai from 'chai';
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import * as chaiAsPromised from 'chai-as-promised';
 chai.use(chaiAsPromised);
 const expect = chai.expect;
-const expectFileExists = (path: string) => expect(fs.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
+const expectFileExists = (path: string) => expect(fsAsPromised.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
 
 describe('Verify stryker has ran correctly', () => {
 
diff --git a/integrationTest/test/command/verify/verify.ts b/integrationTest/test/command/verify/verify.ts
index ce549d4c0e..52198a635f 100644
--- a/integrationTest/test/command/verify/verify.ts
+++ b/integrationTest/test/command/verify/verify.ts
@@ -1,4 +1,4 @@
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import { expect } from 'chai';
 import * as path from 'path';
 import { readScoreResult } from '../../../helpers';
@@ -12,7 +12,7 @@ describe('After running stryker with the command test runner', () => {
   });
 
   it('should write to a log file', async () => {
-    const strykerLog = await fs.readFile('./stryker.log', 'utf8');
+    const strykerLog = await fsAsPromised.readFile('./stryker.log', 'utf8');
     expect(strykerLog).contains('INFO InitialTestExecutor Initial test run succeeded. Ran 1 test');
     expect(strykerLog).matches(/Stryker Done in \d+/);
     expect(strykerLog).not.contains('ERROR');
diff --git a/integrationTest/test/jasmine-jasmine/package.json b/integrationTest/test/jasmine-jasmine/package.json
index 80274018cb..8e8ea435ac 100644
--- a/integrationTest/test/jasmine-jasmine/package.json
+++ b/integrationTest/test/jasmine-jasmine/package.json
@@ -5,7 +5,7 @@
   "description": "A module to perform an integration test",
   "main": "index.js",
   "scripts": {
-    "pretest": "rimraf \"reports\" \"verify/*.map\" \"stryker.log\"",
+    "pretest": "rimraf \"reports\" \"stryker.log\"",
     "test": "stryker run",
     "posttest": "mocha --require ts-node/register verify/*.ts"
   },
diff --git a/integrationTest/test/jasmine-jasmine/verify/verify.ts b/integrationTest/test/jasmine-jasmine/verify/verify.ts
index 17ab17045f..fae5682036 100644
--- a/integrationTest/test/jasmine-jasmine/verify/verify.ts
+++ b/integrationTest/test/jasmine-jasmine/verify/verify.ts
@@ -1,4 +1,4 @@
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import { expect } from 'chai';
 import { readScoreResult } from '../../../helpers';
 
@@ -11,7 +11,7 @@ describe('After running stryker with test runner jasmine, test framework jasmine
   });
 
   it('should write to a log file', async () => {
-    const strykerLog = await fs.readFile('./stryker.log', 'utf8');
+    const strykerLog = await fsAsPromised.readFile('./stryker.log', 'utf8');
     expect(strykerLog).contains('INFO InputFileResolver Found 2 of 10 file(s) to be mutated');
     expect(strykerLog).matches(/Stryker Done in \d+/);
     // TODO, we now have an error because of a memory leak: https://github.com/jasmine/jasmine-npm/issues/134
diff --git a/integrationTest/test/jest-react/package.json b/integrationTest/test/jest-react/package.json
index e493ecc36d..72d1c5568a 100644
--- a/integrationTest/test/jest-react/package.json
+++ b/integrationTest/test/jest-react/package.json
@@ -16,6 +16,7 @@
   "localDependencies": {
     "stryker": "../../../packages/stryker",
     "stryker-javascript-mutator": "../../../packages/stryker-javascript-mutator",
-    "stryker-jest-runner": "../../../packages/stryker-jest-runner"
+    "stryker-jest-runner": "../../../packages/stryker-jest-runner",
+    "@stryker-mutator/util": "../../../packages/stryker-util"
   }
 }
diff --git a/integrationTest/test/jest-react/verify/verify.ts b/integrationTest/test/jest-react/verify/verify.ts
index a944fa5e93..ed977e2782 100644
--- a/integrationTest/test/jest-react/verify/verify.ts
+++ b/integrationTest/test/jest-react/verify/verify.ts
@@ -1,4 +1,4 @@
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import { expect } from 'chai';
 import * as path from 'path';
 import { ScoreResult } from 'stryker-api/report';
@@ -6,10 +6,10 @@ import { ScoreResult } from 'stryker-api/report';
 describe('After running stryker on angular project', () => {
   it('should report 50% mutation score', async () => {
     const eventsDir = path.resolve(__dirname, '..', 'reports', 'mutation', 'events');
-    const allReportFiles = await fs.readdir(eventsDir);
+    const allReportFiles = await fsAsPromised.readdir(eventsDir);
     const scoreResultReportFile = allReportFiles.find(file => !!file.match(/.*onScoreCalculated.*/));
     expect(scoreResultReportFile).ok;
-    const scoreResultContent = await fs.readFile(path.resolve(eventsDir, scoreResultReportFile || ''), 'utf8');
+    const scoreResultContent = await fsAsPromised.readFile(path.resolve(eventsDir, scoreResultReportFile || ''), 'utf8');
     const scoreResult = JSON.parse(scoreResultContent) as ScoreResult;
     expect(scoreResult.killed).eq(1);
     expect(scoreResult.survived).eq(1);
diff --git a/integrationTest/test/karma-jasmine/package.json b/integrationTest/test/karma-jasmine/package.json
index 8858ef5880..df581d57d0 100644
--- a/integrationTest/test/karma-jasmine/package.json
+++ b/integrationTest/test/karma-jasmine/package.json
@@ -5,9 +5,9 @@
   "description": "A module to perform an integration test",
   "main": "index.js",
   "scripts": {
-    "pretest": "rimraf \"reports\" \"verify/*.js\" \"verify/*.map\" && tsc -p .",
+    "pretest": "rimraf \"reports\"",
     "test": "stryker run stryker.conf.js",
-    "posttest": "mocha verify/*.js"
+    "posttest": "mocha --require ts-node/register verify/*.ts"
   },
   "author": "",
   "license": "ISC"
diff --git a/integrationTest/test/karma-jasmine/verify/verify.ts b/integrationTest/test/karma-jasmine/verify/verify.ts
index e5d7ec2736..db23c197e4 100644
--- a/integrationTest/test/karma-jasmine/verify/verify.ts
+++ b/integrationTest/test/karma-jasmine/verify/verify.ts
@@ -1,9 +1,9 @@
 import * as chai from 'chai';
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import * as chaiAsPromised from 'chai-as-promised';
 chai.use(chaiAsPromised);
 const expect = chai.expect;
-const expectFileExists = (path: string) => expect(fs.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
+const expectFileExists = (path: string) => expect(fsAsPromised.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
 
 describe('Verify stryker has ran correctly', () => {
 
diff --git a/integrationTest/test/karma-mocha/package.json b/integrationTest/test/karma-mocha/package.json
index 8858ef5880..df581d57d0 100644
--- a/integrationTest/test/karma-mocha/package.json
+++ b/integrationTest/test/karma-mocha/package.json
@@ -5,9 +5,9 @@
   "description": "A module to perform an integration test",
   "main": "index.js",
   "scripts": {
-    "pretest": "rimraf \"reports\" \"verify/*.js\" \"verify/*.map\" && tsc -p .",
+    "pretest": "rimraf \"reports\"",
     "test": "stryker run stryker.conf.js",
-    "posttest": "mocha verify/*.js"
+    "posttest": "mocha --require ts-node/register verify/*.ts"
   },
   "author": "",
   "license": "ISC"
diff --git a/integrationTest/test/karma-mocha/verify/verify.ts b/integrationTest/test/karma-mocha/verify/verify.ts
index e5d7ec2736..db23c197e4 100644
--- a/integrationTest/test/karma-mocha/verify/verify.ts
+++ b/integrationTest/test/karma-mocha/verify/verify.ts
@@ -1,9 +1,9 @@
 import * as chai from 'chai';
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import * as chaiAsPromised from 'chai-as-promised';
 chai.use(chaiAsPromised);
 const expect = chai.expect;
-const expectFileExists = (path: string) => expect(fs.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
+const expectFileExists = (path: string) => expect(fsAsPromised.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
 
 describe('Verify stryker has ran correctly', () => {
 
diff --git a/integrationTest/test/mocha-mocha/verify/verify.ts b/integrationTest/test/mocha-mocha/verify/verify.ts
index 7ebf5b8d13..a04c8d8e80 100644
--- a/integrationTest/test/mocha-mocha/verify/verify.ts
+++ b/integrationTest/test/mocha-mocha/verify/verify.ts
@@ -1,9 +1,9 @@
 import * as chai from 'chai';
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import * as chaiAsPromised from 'chai-as-promised';
 chai.use(chaiAsPromised);
 const expect = chai.expect;
-const expectFileExists = (path: string) => expect(fs.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
+const expectFileExists = (path: string) => expect(fsAsPromised.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
 
 describe('Verify stryker has ran correctly', () => {
 
diff --git a/integrationTest/test/typescript-transpiling/verify/verify.ts b/integrationTest/test/typescript-transpiling/verify/verify.ts
index 535566ed53..50263090b2 100644
--- a/integrationTest/test/typescript-transpiling/verify/verify.ts
+++ b/integrationTest/test/typescript-transpiling/verify/verify.ts
@@ -1,9 +1,9 @@
 import * as chai from 'chai';
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import * as chaiAsPromised from 'chai-as-promised';
 chai.use(chaiAsPromised);
 const expect = chai.expect;
-const expectFileExists = (path: string) => expect(fs.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
+const expectFileExists = (path: string) => expect(fsAsPromised.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
 
 describe('Verify stryker has ran correctly', () => {
 
diff --git a/integrationTest/test/use-stryker-programmatically/package.json b/integrationTest/test/use-stryker-programmatically/package.json
index d1f559857d..a066fec057 100644
--- a/integrationTest/test/use-stryker-programmatically/package.json
+++ b/integrationTest/test/use-stryker-programmatically/package.json
@@ -3,7 +3,6 @@
   "version": "0.0.0",
   "private": true,
   "scripts": {
-    "pretest": "tsc -p .",
-    "test": "node usingStryker.js"
+    "test": "node --require ts-node/register usingStryker.ts"
   }
 }
diff --git a/integrationTest/test/use-stryker-programmatically/usingStryker.js b/integrationTest/test/use-stryker-programmatically/usingStryker.js
deleted file mode 100644
index a8d3dfffbc..0000000000
--- a/integrationTest/test/use-stryker-programmatically/usingStryker.js
+++ /dev/null
@@ -1,9 +0,0 @@
-"use strict";
-Object.defineProperty(exports, "__esModule", { value: true });
-var stryker_1 = require("stryker");
-new stryker_1.default({
-    testRunner: 'mocha',
-    mutate: [],
-    coverageAnalysis: 'off',
-    files: []
-}).runMutationTest().then(function () { return console.log('done'); });
diff --git a/integrationTest/test/vue-javascript/package.json b/integrationTest/test/vue-javascript/package.json
index 7d3352640e..85f3d49152 100644
--- a/integrationTest/test/vue-javascript/package.json
+++ b/integrationTest/test/vue-javascript/package.json
@@ -9,9 +9,9 @@
     "dev": "webpack-dev-server --inline --progress --config build/webpack.dev.conf.js",
     "start": "npm run dev",
     "unit": "cross-env BABEL_ENV=test karma start test/unit/karma.conf.js --single-run",
-    "pretest": "rimraf \"reports\" \"verify/*.js\" \"verify/*.map\" && tsc -p .",
+    "pretest": "rimraf \"reports\"",
     "test": "stryker run stryker.conf.js",
-    "posttest": "mocha verify/*.js",
+    "posttest": "mocha --require ts-node/register verify/*.ts",
     "lint": "eslint --ext .js,.vue src test/unit",
     "build": "node build/build.js"
   },
@@ -85,9 +85,10 @@
   },
   "localDependencies": {
     "stryker": "../../../packages/stryker",
+    "stryker-javascript-mutator": "../../../packages/stryker-javascript-mutator",
     "stryker-karma-runner": "../../../packages/stryker-karma-runner",
     "stryker-vue-mutator": "../../../packages/stryker-vue-mutator",
-    "stryker-javascript-mutator": "../../../packages/stryker-javascript-mutator"
+    "@stryker-mutator/util": "../../../packages/stryker-util"
   },
   "engines": {
     "node": ">= 6.0.0",
diff --git a/integrationTest/test/vue-javascript/verify/verify.ts b/integrationTest/test/vue-javascript/verify/verify.ts
index 6b835c4e87..606dfef323 100644
--- a/integrationTest/test/vue-javascript/verify/verify.ts
+++ b/integrationTest/test/vue-javascript/verify/verify.ts
@@ -1,4 +1,4 @@
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import { expect } from 'chai';
 import * as path from 'path';
 import { ScoreResult } from 'stryker-api/report';
@@ -6,10 +6,10 @@ import { ScoreResult } from 'stryker-api/report';
 describe('After running stryker on VueJS project', () => {
   it('should report 25% mutation score', async () => {
     const eventsDir = path.resolve(__dirname, '..', 'reports', 'mutation', 'events');
-    const allReportFiles = await fs.readdir(eventsDir);
+    const allReportFiles = await fsAsPromised.readdir(eventsDir);
     const scoreResultReportFile = allReportFiles.find(file => !!file.match(/.*onScoreCalculated.*/));
     expect(scoreResultReportFile).ok;
-    const scoreResultContent = await fs.readFile(path.resolve(eventsDir, scoreResultReportFile || ''), 'utf8');
+    const scoreResultContent = await fsAsPromised.readFile(path.resolve(eventsDir, scoreResultReportFile || ''), 'utf8');
     const scoreResult = JSON.parse(scoreResultContent) as ScoreResult;
     expect(scoreResult.killed).eq(4);
     expect(scoreResult.survived).eq(12);
diff --git a/integrationTest/test/webpack-zero-conf-karma/verify/verify.ts b/integrationTest/test/webpack-zero-conf-karma/verify/verify.ts
index 225bccd5ff..95b55f572c 100644
--- a/integrationTest/test/webpack-zero-conf-karma/verify/verify.ts
+++ b/integrationTest/test/webpack-zero-conf-karma/verify/verify.ts
@@ -1,9 +1,9 @@
 import * as chai from 'chai';
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import * as chaiAsPromised from 'chai-as-promised';
 chai.use(chaiAsPromised);
 const expect = chai.expect;
-const expectFileExists = (path: string) => expect(fs.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
+const expectFileExists = (path: string) => expect(fsAsPromised.exists(path), `File ${path} does not exist`).to.eventually.eq(true);
 function expectMutationScore(score: string, annotation: string, actualContent: string) {
   const isMatch = new RegExp(`<th\\s+class="[^"]* text-${annotation}"[^>]*>${score}<\\/th>`, 'g').test(actualContent);
   expect(isMatch, `Mutation score ${score} with annotation ${annotation} not found in ${actualContent}`).is.ok;
@@ -15,8 +15,8 @@ describe('Verify stryker has ran correctly', () => {
       expectFileExists('reports/mutation/html/index.html'),
     ]);
   });
-  it('should contain the correct mutation score', () => {
-    const indexContent = fs.readFileSync('reports/mutation/html/index.html', 'utf8');
+  it('should contain the correct mutation score', async () => {
+    const indexContent = await fsAsPromised.readFile('reports/mutation/html/index.html', 'utf8');
     expectMutationScore('33.33', 'danger', indexContent);
   });
 });
diff --git a/package.json b/package.json
index e89ec819fb..5ef3973e02 100644
--- a/package.json
+++ b/package.json
@@ -14,8 +14,6 @@
     "@types/lodash": "^4.14.110",
     "@types/mkdirp": "^0.5.2",
     "@types/mocha": "^2.2.44",
-    "@types/mz": "0.0.32",
-    "@types/node": "^6.0.114",
     "@types/rimraf": "2.0.2",
     "@types/sinon": "^5.0.1",
     "@types/sinon-chai": "^3.2.0",
@@ -54,5 +52,8 @@
   "engines": {
     "node": ">=6",
     "npm": ">=5"
+  },
+  "dependencies": {
+    "@types/node": "^10.11.5"
   }
 }
diff --git a/packages/stryker-api/test/integration/install-module/install-module.ts b/packages/stryker-api/test/integration/install-module/install-module.ts
index 4659b4169a..97285f9ad8 100644
--- a/packages/stryker-api/test/integration/install-module/install-module.ts
+++ b/packages/stryker-api/test/integration/install-module/install-module.ts
@@ -1,5 +1,5 @@
 import { expect } from 'chai';
-import { exec } from 'mz/child_process';
+import { exec } from 'child_process';
 import * as path from 'path';
 
 describe('we have a module using stryker', function() {
diff --git a/packages/stryker-babel-transpiler/test/helpers/projectLoader.ts b/packages/stryker-babel-transpiler/test/helpers/projectLoader.ts
index 67f8bf9d67..1aba524ccc 100644
--- a/packages/stryker-babel-transpiler/test/helpers/projectLoader.ts
+++ b/packages/stryker-babel-transpiler/test/helpers/projectLoader.ts
@@ -1,10 +1,22 @@
-import * as fs from 'mz/fs';
+import * as fs from 'fs';
 import * as path from 'path';
 import { File } from 'stryker-api/core';
 import * as glob from 'glob';
 
 const CARRIAGE_RETURN = '\r'.charCodeAt(0);
 
+function readFile(fileName: string) {
+  return new Promise<Buffer>((res, rej) => {
+    fs.readFile(fileName, (err, result) => {
+      if (err) {
+        rej(err);
+      } else {
+        res(result);
+      }
+    });
+  });
+}
+
 export class ProjectLoader {
 
   public static getFiles(basePath: string) {
@@ -16,7 +28,7 @@ export class ProjectLoader {
     return this.glob(basePath)
       .then(fileNames => fileNames.map(fileName => path.join(basePath, fileName)))
       .then(fileNames => Promise.all(fileNames.map(fileName =>
-        fs.readFile(fileName).then(content => new File(fileName, this.normalize(content))))));
+        readFile(fileName).then(content => new File(fileName, this.normalize(content))))));
   }
 
   private static normalize(content: Buffer) {
diff --git a/packages/stryker-html-reporter/package.json b/packages/stryker-html-reporter/package.json
index ac03b1985b..a909836a70 100644
--- a/packages/stryker-html-reporter/package.json
+++ b/packages/stryker-html-reporter/package.json
@@ -41,6 +41,7 @@
     "mkdirp": "~0.5.1",
     "mz": "~2.7.0",
     "rimraf": "~2.6.1",
+    "@stryker-mutator/util": "~0.0.0",
     "typed-html": "~0.6.0"
   },
   "peerDependencies": {
@@ -48,8 +49,8 @@
   },
   "devDependencies": {
     "@types/file-url": "~2.0.0",
+    "@types/node": "^10.11.5",
     "@types/jsdom": "~12.2.0",
-    "@types/node": "~6.14.0",
     "bootstrap": "4.1.3",
     "highlight.js": "~9.13.0",
     "jquery": "~3.3.1",
diff --git a/packages/stryker-html-reporter/src/util.ts b/packages/stryker-html-reporter/src/util.ts
index 948c581800..e0c46ee64a 100644
--- a/packages/stryker-html-reporter/src/util.ts
+++ b/packages/stryker-html-reporter/src/util.ts
@@ -1,29 +1,29 @@
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import * as path from 'path';
 import * as mkdirp from 'mkdirp';
 import * as rimraf from 'rimraf';
 
-function copyFolderOrFile(fromPath: string, toPath: string): Promise<void> {
-  return fs.stat(fromPath).then(stats => {
-    if (stats.isDirectory()) {
-      return copyFolder(fromPath, toPath);
-    } else {
-      return copyFile(fromPath, toPath);
-    }
-  });
+async function copyFolderOrFile(fromPath: string, toPath: string): Promise<void> {
+  const stats = await fsAsPromised.stat(fromPath);
+  if (stats.isDirectory()) {
+    return copyFolder(fromPath, toPath);
+  }
+  else {
+    return copyFile(fromPath, toPath);
+  }
 }
 
 export function copyFolder(fromPath: string, to: string): Promise<void> {
   return mkdir(to)
-    .then(() => fs.readdir(fromPath))
+    .then(() => fsAsPromised.readdir(fromPath))
     .then(files => Promise.all(files.map(file => copyFolderOrFile(path.join(fromPath, file), path.join(to, file)))))
     .then(_ => void 0);
 }
 
 function copyFile(fromFilename: string, toFilename: string): Promise<void> {
   return new Promise<void>((resolve, reject) => {
-    const readStream = fs.createReadStream(fromFilename);
-    const writeStream = fs.createWriteStream(toFilename);
+    const readStream = fsAsPromised.createReadStream(fromFilename);
+    const writeStream = fsAsPromised.createWriteStream(toFilename);
     readStream.on('error', reject);
     writeStream.on('error', reject);
     readStream.pipe(writeStream);
@@ -57,7 +57,7 @@ export function mkdir(folderName: string): Promise<void> {
 
 export function writeFile(fileName: string, content: string) {
   return mkdir(path.dirname(fileName))
-    .then(_ => fs.writeFile(fileName, content, 'utf8'));
+    .then(_ => fsAsPromised.writeFile(fileName, content, 'utf8'));
 }
 
 export function countPathSep(fileName: string) {
diff --git a/packages/stryker-html-reporter/tasks/clientResources.js b/packages/stryker-html-reporter/tasks/clientResources.js
index a4e2e48b11..9c6980b517 100644
--- a/packages/stryker-html-reporter/tasks/clientResources.js
+++ b/packages/stryker-html-reporter/tasks/clientResources.js
@@ -1,7 +1,7 @@
 const path = require('path');
 const glob = require('glob');
 const mkdirp = require('mkdirp');
-const fs = require('mz/fs');
+const fs = require('fs');
 const rimraf = require('rimraf');
 
 const callbackAsPromised = (res, rej) => (err, result) => {
diff --git a/packages/stryker-html-reporter/test/helpers/EventPlayer.ts b/packages/stryker-html-reporter/test/helpers/EventPlayer.ts
index c571952265..0af7a9f3fe 100644
--- a/packages/stryker-html-reporter/test/helpers/EventPlayer.ts
+++ b/packages/stryker-html-reporter/test/helpers/EventPlayer.ts
@@ -1,6 +1,6 @@
 import * as path from 'path';
 import { Reporter } from 'stryker-api/report';
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 
 const eventName = (filename: string) =>
   filename.substring(filename.indexOf('-') + 1, filename.indexOf('.'));
@@ -9,9 +9,9 @@ export default class EventPlayer {
   constructor(private readonly fromDirectory: string) { }
 
   public replay(target: Reporter) {
-    const files = fs.readdirSync(this.fromDirectory).sort();
+    const files = fsAsPromised.readdirSync(this.fromDirectory).sort();
     return Promise.all(files.map(
-      filename => fs.readFile(path.join(this.fromDirectory, filename), 'utf8').then(content => ({
+      filename => fsAsPromised.readFile(path.join(this.fromDirectory, filename), 'utf8').then(content => ({
         content: JSON.parse(this.replacePathSeparator(content)),
         name: eventName(filename)
       }))
diff --git a/packages/stryker-html-reporter/test/helpers/fsHelpers.ts b/packages/stryker-html-reporter/test/helpers/fsHelpers.ts
index f8a4bdc51c..9ba734854d 100644
--- a/packages/stryker-html-reporter/test/helpers/fsHelpers.ts
+++ b/packages/stryker-html-reporter/test/helpers/fsHelpers.ts
@@ -1,5 +1,5 @@
 import * as path from 'path';
-import { fs } from 'mz';
+import * as fs from 'fs';
 
 type File = string | Directory;
 
diff --git a/packages/stryker-html-reporter/test/integration/singleFileInFolderSpec.ts b/packages/stryker-html-reporter/test/integration/singleFileInFolderSpec.ts
index babba3e3b4..4d3d8fd9cd 100644
--- a/packages/stryker-html-reporter/test/integration/singleFileInFolderSpec.ts
+++ b/packages/stryker-html-reporter/test/integration/singleFileInFolderSpec.ts
@@ -4,7 +4,7 @@ import { Config } from 'stryker-api/config';
 import EventPlayer from '../helpers/EventPlayer';
 import HtmlReporter from '../../src/HtmlReporter';
 import { readDirectoryTree } from '../helpers/fsHelpers';
-import { fs } from 'mz';
+import * as fs from 'fs';
 
 const REPORT_DIR = 'reports/mutation/singleFileInFolder';
 
diff --git a/packages/stryker-jest-runner/testResources/reactTsProject/package.json b/packages/stryker-jest-runner/testResources/reactTsProject/package.json
index 27d2dff977..d32f82df9c 100644
--- a/packages/stryker-jest-runner/testResources/reactTsProject/package.json
+++ b/packages/stryker-jest-runner/testResources/reactTsProject/package.json
@@ -15,7 +15,6 @@
   },
   "devDependencies": {
     "@types/jest": "^22.2.3",
-    "@types/node": "^9.6.4",
     "@types/react": "^16.3.9",
     "@types/react-dom": "^16.0.5",
     "typescript": "^2.8.1"
diff --git a/packages/stryker-typescript/test/unit/TypescriptMutatorSpec.ts b/packages/stryker-typescript/test/unit/TypescriptMutatorSpec.ts
index e4636c65dc..4a391a9e8b 100644
--- a/packages/stryker-typescript/test/unit/TypescriptMutatorSpec.ts
+++ b/packages/stryker-typescript/test/unit/TypescriptMutatorSpec.ts
@@ -1,5 +1,5 @@
 import * as path from 'path';
-import * as fs from 'mz/fs';
+import * as fs from 'fs';
 import { expect } from 'chai';
 import * as ts from 'typescript';
 import { Config } from 'stryker-api/config';
diff --git a/packages/stryker-util/.vscode/launch.json b/packages/stryker-util/.vscode/launch.json
new file mode 100644
index 0000000000..a949b9d86f
--- /dev/null
+++ b/packages/stryker-util/.vscode/launch.json
@@ -0,0 +1,48 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "type": "node",
+      "request": "launch",
+      "name": "Unit tests",
+      "program": "${workspaceFolder}/../../node_modules/mocha/bin/_mocha",
+      "args": [
+        "-u",
+        "tdd",
+        "--timeout",
+        "999999",
+        "--colors",
+        "${workspaceFolder}/test/helpers/**/*.js",
+        "${workspaceFolder}/test/unit/**/*.js"
+      ],
+      "internalConsoleOptions": "openOnSessionStart",
+      "outFiles": [
+        "${workspaceRoot}/test/**/*.js",
+        "${workspaceRoot}/src/**/*.js"
+      ]
+    },
+    {
+      "type": "node",
+      "request": "launch",
+      "name": "Integration tests",
+      "program": "${workspaceFolder}/../../node_modules/mocha/bin/_mocha",
+      "args": [
+        "-u",
+        "tdd",
+        "--timeout",
+        "999999",
+        "--colors",
+        "${workspaceFolder}/test/helpers/**/*.js",
+        "${workspaceFolder}/test/integration/**/*.js"
+      ],
+      "internalConsoleOptions": "openOnSessionStart",
+      "outFiles": [
+        "${workspaceRoot}/test/**/*.js",
+        "${workspaceRoot}/src/**/*.js"
+      ]
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/stryker-util/.vscode/settings.json b/packages/stryker-util/.vscode/settings.json
new file mode 100644
index 0000000000..75776c1ebe
--- /dev/null
+++ b/packages/stryker-util/.vscode/settings.json
@@ -0,0 +1,13 @@
+{
+  "files.exclude": {
+    ".git": true,
+    ".tscache": true,
+    "**/*.js": {
+      "when": "$(basename).ts"
+    },
+    "**/*.d.ts": true,
+    "**/*.map": {
+      "when": "$(basename)"
+    }
+  }
+}
\ No newline at end of file
diff --git a/packages/stryker-util/.vscode/tasks.json b/packages/stryker-util/.vscode/tasks.json
new file mode 100644
index 0000000000..9b8051bdab
--- /dev/null
+++ b/packages/stryker-util/.vscode/tasks.json
@@ -0,0 +1,18 @@
+{
+  // See https://go.microsoft.com/fwlink/?LinkId=733558
+  // for the documentation about the tasks.json format
+  "version": "2.0.0",
+  "tasks": [
+    {
+      "label": "tsc-watch",
+      "type": "shell",
+      "command": "npm start",
+      "problemMatcher": "$tsc-watch",
+      "isBackground": true,
+      "group": {
+        "kind": "build",
+        "isDefault": true
+      }
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/stryker-util/README.md b/packages/stryker-util/README.md
new file mode 100644
index 0000000000..2944b2e6af
--- /dev/null
+++ b/packages/stryker-util/README.md
@@ -0,0 +1,10 @@
+[![Build Status](https://travis-ci.org/stryker-mutator/stryker.svg?branch=master)](https://travis-ci.org/stryker-mutator/stryker)
+[![NPM](https://img.shields.io/npm/dm/stryker-utils.svg)](https://www.npmjs.com/package/stryker-utils)
+[![Node version](https://img.shields.io/node/v/stryker-utils.svg)](https://img.shields.io/node/v/stryker-utils.svg)
+[![Gitter](https://badges.gitter.im/stryker-mutator/stryker.svg)](https://gitter.im/stryker-mutator/stryker?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
+
+![Stryker](https://github.com/stryker-mutator/stryker/raw/master/stryker-80x80.png)
+
+# Stryker Util
+
+Utility functions for Stryker plugins and/or core packages.
diff --git a/packages/stryker-util/package.json b/packages/stryker-util/package.json
new file mode 100644
index 0000000000..1e43a28f56
--- /dev/null
+++ b/packages/stryker-util/package.json
@@ -0,0 +1,29 @@
+{
+  "name": "@stryker-mutator/util",
+  "version": "0.0.0",
+  "description": "Contains utilities for Stryker, the mutation testing framework for JavaScript and friends",
+  "main": "src/index.js",
+  "typings": "src/index.d.ts",
+  "scripts": {
+    "start": "tsc -w",
+    "clean": "rimraf \"+(test|src)/**/*+(.d.ts|.js|.map)\" reports",
+    "prebuild": "npm run clean",
+    "build": "tsc -p .",
+    "postbuild": "tslint -p tsconfig.json",
+    "test": "nyc --check-coverage --reporter=html --report-dir=reports/coverage --lines 90 --functions 95 --branches 75 mocha \"test/helpers/**/*.js\" \"test/unit/**/*.js\" \"test/integration/**/*.js\""
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/stryker-mutator/stryker.git"
+  },
+  "keywords": [
+    "stryker",
+    "utils"
+  ],
+  "author": "Nico Jansen <jansennico@gmail.com>",
+  "license": "Apache-2.0",
+  "bugs": {
+    "url": "https://github.com/stryker-mutator/stryker/issues"
+  },
+  "homepage": "https://github.com/stryker-mutator/stryker/tree/master/packages/@stryker-mutator/util#readme"
+}
diff --git a/packages/stryker-util/src/childProcessAsPromised.ts b/packages/stryker-util/src/childProcessAsPromised.ts
new file mode 100644
index 0000000000..bb7022a137
--- /dev/null
+++ b/packages/stryker-util/src/childProcessAsPromised.ts
@@ -0,0 +1,6 @@
+import * as childProcess from 'child_process';
+import promisify from './promisify';
+
+export default {
+  exec: promisify(childProcess.exec)
+};
diff --git a/packages/stryker-util/src/fsAsPromised.ts b/packages/stryker-util/src/fsAsPromised.ts
new file mode 100644
index 0000000000..644c83d866
--- /dev/null
+++ b/packages/stryker-util/src/fsAsPromised.ts
@@ -0,0 +1,21 @@
+import * as fs from 'fs';
+import promisify from './promisify';
+
+/**
+ * This file contains an implementation of fs.promises
+ * Note: Can be removed once we drop support for node 8 (and 9).
+ */
+
+export default {
+  createReadStream: fs.createReadStream,
+  createWriteStream: fs.createWriteStream,
+  exists: promisify(fs.exists),
+  existsSync: fs.existsSync,
+  lstat: promisify(fs.lstat),
+  readdir: promisify(fs.readdir),
+  readdirSync: fs.readdirSync,
+  readFile: promisify(fs.readFile),
+  stat: promisify(fs.stat),
+  symlink: promisify(fs.symlink),
+  writeFile: promisify(fs.writeFile),
+};
diff --git a/packages/stryker-util/src/index.ts b/packages/stryker-util/src/index.ts
new file mode 100644
index 0000000000..52dd2b3016
--- /dev/null
+++ b/packages/stryker-util/src/index.ts
@@ -0,0 +1,3 @@
+export { default as fsAsPromised } from './fsAsPromised';
+export { default as childProcessAsPromised } from './childProcessAsPromised';
+export { default as promisify } from './promisify';
diff --git a/packages/stryker-util/src/promisify.ts b/packages/stryker-util/src/promisify.ts
new file mode 100644
index 0000000000..ee346cc10b
--- /dev/null
+++ b/packages/stryker-util/src/promisify.ts
@@ -0,0 +1,45 @@
+import { exec } from 'child_process';
+import { exists } from 'fs';
+import * as util from 'util';
+
+/**
+ * This file contains an implementation of util.promisify (available on node >= 8)
+ * Note: Can be removed once we drop support for node 6 (and 7).
+ */
+function promisify(original: any) {
+  if ('promisify' in util) {
+    return util.promisify(original); // let nodejs do it's thing thing, if it is supported
+  } else {
+    return innerPromisify(original); // Do it ourselves
+  }
+}
+
+// This function is exported so that it can be tested on node >= 8
+export function innerPromisify(original: any) {
+  return function fn(...args: any[]) {
+    return new Promise((resolve, reject) => {
+      original.call(this, ...args, (err: Error, ...values: any[]) => {
+        if (original === exists) {
+          // the exists callback is NOT consistent with NodeJS callbacks: https://nodejs.org/api/fs.html#fs_fs_exists_path_callback
+          // First argument is the result instead of an error
+          resolve(err);
+        } else if (err) {
+          reject(err);
+        } else {
+          // Make an exception for child_process.exec, this is also done by node 8+'s implementation
+          // https://github.com/nodejs/node/blob/2ec57a71343cdb725d45801508fceb0a266a9324/lib/internal/util.js#L272
+          if (original === exec) {
+            resolve({
+              stderr: values[1],
+              stdout: values[0]
+            });
+          } else {
+            resolve(values[0]);
+          }
+        }
+      });
+    });
+  };
+}
+
+export default promisify as typeof util.promisify;
diff --git a/packages/stryker-util/test/helpers/initSinon.ts b/packages/stryker-util/test/helpers/initSinon.ts
new file mode 100644
index 0000000000..b168594f22
--- /dev/null
+++ b/packages/stryker-util/test/helpers/initSinon.ts
@@ -0,0 +1,5 @@
+import * as sinon from 'sinon';
+
+afterEach(() => {
+  sinon.restore();
+});
diff --git a/packages/stryker-util/test/helpers/initSourceMaps.ts b/packages/stryker-util/test/helpers/initSourceMaps.ts
new file mode 100644
index 0000000000..fcfbfda16c
--- /dev/null
+++ b/packages/stryker-util/test/helpers/initSourceMaps.ts
@@ -0,0 +1 @@
+import 'source-map-support/register';
diff --git a/packages/stryker-util/test/helpers/registerChaiPlugins.ts b/packages/stryker-util/test/helpers/registerChaiPlugins.ts
new file mode 100644
index 0000000000..3f9437376e
--- /dev/null
+++ b/packages/stryker-util/test/helpers/registerChaiPlugins.ts
@@ -0,0 +1,5 @@
+import * as sinonChai from 'sinon-chai';
+import * as chaiAsPromised from 'chai-as-promised';
+import * as chai from 'chai';
+chai.use(sinonChai);
+chai.use(chaiAsPromised);
diff --git a/packages/stryker-util/test/unit/childProcessAsPromised.ts b/packages/stryker-util/test/unit/childProcessAsPromised.ts
new file mode 100644
index 0000000000..548bb66823
--- /dev/null
+++ b/packages/stryker-util/test/unit/childProcessAsPromised.ts
@@ -0,0 +1,10 @@
+import childProcess = require('child_process');
+import { expect } from 'chai';
+import { childProcessAsPromised, promisify } from '../../src';
+
+describe('childProcessAsPromised', () => {
+  it(`should expose promisified exec`, () => {
+    // It's difficult to test this any other way. At least this way, we know it is promisified.
+    expect(childProcessAsPromised.exec.toString()).eq(promisify(childProcess.exec).toString());
+  });
+});
diff --git a/packages/stryker-util/test/unit/fsAsPromisedSpec.ts b/packages/stryker-util/test/unit/fsAsPromisedSpec.ts
new file mode 100644
index 0000000000..ff65c66fd3
--- /dev/null
+++ b/packages/stryker-util/test/unit/fsAsPromisedSpec.ts
@@ -0,0 +1,33 @@
+import fs = require('fs');
+import { expect } from 'chai';
+import { fsAsPromised, promisify } from '../../src';
+
+describe('fsAsPromised', () => {
+
+  describePromisifiedFunction('exists');
+  describePromisifiedFunction('lstat');
+  describePromisifiedFunction('symlink');
+  describePromisifiedFunction('readFile');
+  describePromisifiedFunction('writeFile');
+  describePromisifiedFunction('stat');
+  describePromisifiedFunction('readdir');
+
+  describeProxyFunction('existsSync');
+  describeProxyFunction('readdirSync');
+  describeProxyFunction('createReadStream');
+  describeProxyFunction('createWriteStream');
+
+  function describeProxyFunction(fnToTest: keyof typeof fs & keyof typeof fsAsPromised) {
+    it(`should proxy ${fnToTest}`, () => {
+      // It's difficult to test this any other way. At least this way, we know it is promisified.
+      expect(fsAsPromised[fnToTest]).eq(fs[fnToTest]);
+    });
+  }
+
+  function describePromisifiedFunction(fnToTest: keyof typeof fs & keyof typeof fsAsPromised) {
+    it(`should expose promisified ${fnToTest}`, () => {
+      // It's difficult to test this any other way. At least this way, we know it is promisified.
+      expect(fsAsPromised[fnToTest].toString()).eq(promisify(fs[fnToTest]).toString());
+    });
+  }
+});
diff --git a/packages/stryker-util/test/unit/promisifySpec.ts b/packages/stryker-util/test/unit/promisifySpec.ts
new file mode 100644
index 0000000000..de47ad7bcd
--- /dev/null
+++ b/packages/stryker-util/test/unit/promisifySpec.ts
@@ -0,0 +1,60 @@
+import promisify, { innerPromisify } from '../../src/promisify';
+import * as sinon from 'sinon';
+import { expect } from 'chai';
+import { exec } from 'child_process';
+import { exists } from 'fs';
+
+describe('promisify', () => {
+  describePromisify(promisify);
+});
+
+describe('innerPromisify', () => {
+  describePromisify(innerPromisify);
+});
+
+function describePromisify(promisifyImplementation: any) {
+
+  it('should resolve the promise when the callback resolves', async () => {
+    // Arrange
+    const actualCallbackFn = sinon.stub();
+
+    // Act
+    const actualPromisifiedFn = promisifyImplementation(actualCallbackFn);
+    const actualPromise = actualPromisifiedFn('foo', 42);
+    actualCallbackFn.callArgWith(2, null, 'baz', 42);
+    const actualResult = await actualPromise;
+
+    // Assert
+    expect(actualPromise).instanceOf(Promise);
+    expect(actualCallbackFn).calledWithExactly('foo', 42, sinon.match.func);
+    expect(actualResult).eq('baz');
+  });
+
+  it('should reject the promise when the callback resolved with an error', async () => {
+    // Arrange
+    const actualCallbackFn = sinon.stub();
+    const expectedError = new Error('foobar');
+
+    // Act
+    const actualPromisifiedFn = promisifyImplementation(actualCallbackFn);
+    const actualPromise = actualPromisifiedFn('foo', 42);
+    actualCallbackFn.callArgWith(2, expectedError);
+
+    // Assert
+    expect(actualPromise).instanceOf(Promise);
+    expect(actualCallbackFn).calledWithExactly('foo', 42, sinon.match.func);
+    await expect(actualPromise).rejectedWith(expectedError);
+  });
+
+  it('should resolve child_process.exec as an object instead of an array', async () => {
+    const execAsPromised = promisifyImplementation(exec);
+    const result = await execAsPromised('node -p \'"foo"\'');
+    expect(result.stdout.trim()).eq('foo');
+  });
+
+  it('should resolve fs.exists with first argument being result instead of an error', async () => {
+    const existsAsPromised = promisifyImplementation(exists);
+    const result = await existsAsPromised(__filename);
+    expect(result).eq(true);
+  });
+}
diff --git a/packages/stryker-util/tsconfig.json b/packages/stryker-util/tsconfig.json
new file mode 100644
index 0000000000..7321cad4c9
--- /dev/null
+++ b/packages/stryker-util/tsconfig.json
@@ -0,0 +1,9 @@
+{
+    "extends": "../../tsconfig.json",
+    "exclude": [
+        "node_modules",
+        "src/**/*.d.ts",
+        "test/**/*.d.ts",
+        "testResources"
+    ]
+}
\ No newline at end of file
diff --git a/packages/stryker/package.json b/packages/stryker/package.json
index 6f9efa98c6..055a403d29 100644
--- a/packages/stryker/package.json
+++ b/packages/stryker/package.json
@@ -64,12 +64,12 @@
     "lodash": "~4.17.4",
     "log4js": "~3.0.0",
     "mkdirp": "~0.5.1",
-    "mz": "~2.7.0",
     "prettier": "~1.14.0",
     "progress": "~2.0.0",
     "rimraf": "~2.6.1",
     "rxjs": "~6.3.0",
     "source-map": "~0.6.1",
+    "@stryker-mutator/util": "^0.0.0",
     "surrial": "~0.1.3",
     "tree-kill": "~1.2.0",
     "tslib": "~1.9.3",
@@ -79,7 +79,7 @@
     "@types/get-port": "~4.0.0",
     "@types/inquirer": "~0.0.42",
     "@types/istanbul-lib-instrument": "~1.7.0",
-    "@types/node": "^6.0.114",
+    "@types/node": "~10.11.4",
     "@types/prettier": "~1.13.1",
     "@types/progress": "~2.0.1",
     "stryker-api": "^0.21.2"
diff --git a/packages/stryker/src/PluginLoader.ts b/packages/stryker/src/PluginLoader.ts
index 259794700c..431bb5a5ed 100644
--- a/packages/stryker/src/PluginLoader.ts
+++ b/packages/stryker/src/PluginLoader.ts
@@ -1,8 +1,8 @@
-import * as fs from 'mz/fs';
 import * as path from 'path';
 import { getLogger } from 'stryker-api/logging';
 import * as _ from 'lodash';
 import { importModule } from './utils/fileUtils';
+import { fsAsPromised } from '@stryker-mutator/util';
 
 const IGNORED_PACKAGES = ['stryker-cli', 'stryker-api'];
 
@@ -26,7 +26,7 @@ export default class PluginLoader {
           const regexp = new RegExp('^' + pluginExpression.replace('*', '.*'));
 
           this.log.debug('Loading %s from %s', pluginExpression, pluginDirectory);
-          const plugins = fs.readdirSync(pluginDirectory)
+          const plugins = fsAsPromised.readdirSync(pluginDirectory)
             .filter(pluginName => IGNORED_PACKAGES.indexOf(pluginName) === -1 && regexp.test(pluginName))
             .map(pluginName => pluginDirectory + '/' + pluginName);
           if (plugins.length === 0) {
diff --git a/packages/stryker/src/config/ConfigReader.ts b/packages/stryker/src/config/ConfigReader.ts
index 575c4b0014..15e94a0b8d 100644
--- a/packages/stryker/src/config/ConfigReader.ts
+++ b/packages/stryker/src/config/ConfigReader.ts
@@ -1,5 +1,5 @@
 import * as _ from 'lodash';
-import * as fs from 'mz/fs';
+import fs = require('fs');
 import * as path from 'path';
 import { Config } from 'stryker-api/config';
 import { StrykerOptions } from 'stryker-api/core';
diff --git a/packages/stryker/src/globals.ts b/packages/stryker/src/globals.ts
index 7f5149dad6..f8a2e714dd 100644
--- a/packages/stryker/src/globals.ts
+++ b/packages/stryker/src/globals.ts
@@ -9,24 +9,3 @@ interface Event { }
 interface MessageEvent { }
 interface CloseEvent { }
 interface WebSocket { }
-declare namespace NodeJS {
-  type MessageListener = (message: any, sendHandle: any) => void;
-  type UncaughtExceptionListener = (error: Error) => void;
-  type UnhandledRejectionListener = (reason: any, promise: Promise<any>) => void;
-  type RejectionHandledListener = (promise: Promise<any>) => void;
-  export interface Process extends EventEmitter {
-    addListener(event: 'uncaughtException', listener: UncaughtExceptionListener): this;
-    addListener(event: 'unhandledRejection', listener: UnhandledRejectionListener): this;
-    addListener(event: 'rejectionHandled', listener: RejectionHandledListener): this;
-    emit(event: 'uncaughtException', error: Error): boolean;
-    emit(event: 'unhandledRejection', reason: any, promise: Promise<any>): boolean;
-    emit(event: 'rejectionHandled', promise: Promise<any>): boolean;
-    on(event: string, listener: (...args: any[]) => void): this;
-    on(event: 'uncaughtException', listener: UncaughtExceptionListener): this;
-    on(event: 'unhandledRejection', listener: UnhandledRejectionListener): this;
-    on(event: 'rejectionHandled', listener: RejectionHandledListener): this;
-  }
-}
-declare module 'fs' {
-  export function createWriteStream(path: string, options?: string): WriteStream;
-}
diff --git a/packages/stryker/src/initializer/StrykerConfigWriter.ts b/packages/stryker/src/initializer/StrykerConfigWriter.ts
index 1586c776c5..b06e2c22cb 100644
--- a/packages/stryker/src/initializer/StrykerConfigWriter.ts
+++ b/packages/stryker/src/initializer/StrykerConfigWriter.ts
@@ -1,5 +1,5 @@
-import * as fs from 'mz/fs';
 import * as _ from 'lodash';
+import { fsAsPromised } from '@stryker-mutator/util';
 import { getLogger } from 'stryker-api/logging';
 import { StrykerOptions } from 'stryker-api/core';
 import PromptOption from './PromptOption';
@@ -14,7 +14,7 @@ export default class StrykerConfigWriter {
   }
 
   public guardForExistingConfig() {
-    if (fs.existsSync(STRYKER_CONFIG_FILE)) {
+    if (fsAsPromised.existsSync(STRYKER_CONFIG_FILE)) {
       const msg =
         'Stryker config file "stryker.conf.js" already exists in the current directory. Please remove it and try again.';
       this.log.error(msg);
@@ -26,7 +26,7 @@ export default class StrykerConfigWriter {
    * Create stryker.conf.js based on the chosen framework and test runner
    * @function
    */
-  public async write(
+  public write(
     selectedTestRunner: null | PromptOption,
     selectedTestFramework: null | PromptOption,
     selectedMutator: null | PromptOption,
@@ -58,7 +58,7 @@ export default class StrykerConfigWriter {
 
   private writeStrykerConfig(configObject: Partial<StrykerOptions>) {
     this.out('Writing stryker.conf.js...');
-    return fs.writeFile(STRYKER_CONFIG_FILE, this.wrapInModule(configObject));
+    return fsAsPromised.writeFile(STRYKER_CONFIG_FILE, this.wrapInModule(configObject));
   }
 
   private wrapInModule(configObject: Partial<StrykerOptions>) {
diff --git a/packages/stryker/src/input/InputFileResolver.ts b/packages/stryker/src/input/InputFileResolver.ts
index 486fc01846..e728133257 100644
--- a/packages/stryker/src/input/InputFileResolver.ts
+++ b/packages/stryker/src/input/InputFileResolver.ts
@@ -1,6 +1,6 @@
 import * as path from 'path';
-import * as fs from 'mz/fs';
-import { exec } from 'mz/child_process';
+import { fsAsPromised } from '@stryker-mutator/util';
+import { childProcessAsPromised } from '@stryker-mutator/util';
 import { getLogger } from 'stryker-api/logging';
 import { File } from 'stryker-api/core';
 import { glob } from '../utils/fileUtils';
@@ -48,8 +48,8 @@ export default class InputFileResolver {
   }
 
   private resolveFilesUsingGit(): Promise<string[]> {
-    return exec('git ls-files --others --exclude-standard --cached --exclude .stryker-tmp', { maxBuffer: 10 * 1000 * 1024 })
-      .then(([stdout]) => stdout.toString())
+    return childProcessAsPromised.exec('git ls-files --others --exclude-standard --cached --exclude .stryker-tmp', { maxBuffer: 10 * 1000 * 1024 })
+      .then(({stdout}) => stdout.toString())
       .then(output => output.split('\n').map(fileName => fileName.trim()))
       .then(fileNames => fileNames.filter(fileName => fileName).map(fileName => path.resolve(fileName)))
       .catch(error => {
@@ -71,7 +71,7 @@ export default class InputFileResolver {
   }
 
   private readFile(fileName: string): Promise<File | null> {
-    return fs.readFile(fileName).then(content => new File(fileName, content))
+    return fsAsPromised.readFile(fileName).then(content => new File(fileName, content))
       .then(file => {
         this.reportSourceFilesRead(file);
         return file;
diff --git a/packages/stryker/src/reporters/EventRecorderReporter.ts b/packages/stryker/src/reporters/EventRecorderReporter.ts
index e2ae4e6ed4..9ee54db908 100644
--- a/packages/stryker/src/reporters/EventRecorderReporter.ts
+++ b/packages/stryker/src/reporters/EventRecorderReporter.ts
@@ -1,10 +1,10 @@
 import { getLogger } from 'stryker-api/logging';
 import * as path from 'path';
-import * as fs from 'mz/fs';
 import { StrykerOptions } from 'stryker-api/core';
 import { SourceFile, MutantResult, MatchedMutant, Reporter, ScoreResult } from 'stryker-api/report';
 import { cleanFolder } from '../utils/fileUtils';
 import StrictReporter from './StrictReporter';
+import { fsAsPromised } from '@stryker-mutator/util';
 
 const DEFAULT_BASE_FOLDER = 'reports/mutation/events';
 
@@ -36,7 +36,7 @@ export default class EventRecorderReporter implements StrictReporter {
   private writeToFile(methodName: keyof Reporter, data: any) {
     const filename = path.join(this.baseFolder, `${this.format(this.index++)}-${methodName}.json`);
     this.log.debug(`Writing event ${methodName} to file ${filename}`);
-    return fs.writeFile(filename, JSON.stringify(data), { encoding: 'utf8' });
+    return fsAsPromised.writeFile(filename, JSON.stringify(data), { encoding: 'utf8' });
   }
 
   private format(input: number) {
diff --git a/packages/stryker/src/utils/StrykerTempFolder.ts b/packages/stryker/src/utils/StrykerTempFolder.ts
deleted file mode 100644
index a537d46a58..0000000000
--- a/packages/stryker/src/utils/StrykerTempFolder.ts
+++ /dev/null
@@ -1,74 +0,0 @@
-import * as fs from 'mz/fs';
-import * as path from 'path';
-import * as mkdirp from 'mkdirp';
-import { getLogger } from 'stryker-api/logging';
-import { deleteDir } from './fileUtils';
-
-const baseTempFolder = path.join(process.cwd(), '.stryker-tmp');
-const tempFolder = path.join(baseTempFolder, random().toString());
-mkdirp.sync(baseTempFolder);
-mkdirp.sync(tempFolder);
-
-/**
- * Creates a new random folder with the specified prefix.
- * @param prefix The prefix.
- * @returns The path to the folder.
- */
-function createRandomFolder(prefix: string): string {
-  const dir = tempFolder + path.sep + prefix + random();
-  mkdirp.sync(dir);
-  return dir;
-}
-
-/**
- * Creates a random integer number.
- * @returns A random integer.
- */
-function random(): number {
-  return Math.ceil(Math.random() * 10000000);
-}
-
-/**
- * Writes data to a specified file.
- * @param fileName The path to the file.
- * @param data The content of the file.
- * @returns A promise to eventually save the file.
- */
-function writeFile(fileName: string, data: string | Buffer, instrumenter: NodeJS.ReadWriteStream | null = null): Promise<void> {
-  if (Buffer.isBuffer(data)) {
-    return fs.writeFile(fileName, data);
-  } else if (instrumenter) {
-    instrumenter.pipe(fs.createWriteStream(fileName, 'utf8'));
-    return writeToStream(data, instrumenter);
-  } else {
-    return fs.writeFile(fileName, data, 'utf8');
-  }
-}
-
-function writeToStream(data: string | Buffer, stream: NodeJS.WritableStream): Promise<void> {
-  return new Promise((res, rej) => {
-    stream.end(data as string, (err: Error) => {
-      if (err) {
-        rej(err);
-      } else {
-        res();
-      }
-    });
-  });
-}
-
-/**
- * Deletes the Stryker-temp folder
- */
-function clean() {
-  const log = getLogger('StrykerTempFolder');
-  log.debug(`Cleaning stryker temp folder ${baseTempFolder}`);
-  return deleteDir(baseTempFolder)
-    .catch(() => log.info(`Failed to clean stryker temp folder ${baseTempFolder}`));
-}
-
-export default {
-  clean,
-  createRandomFolder,
-  writeFile
-};
diff --git a/packages/stryker/src/utils/TempFolder.ts b/packages/stryker/src/utils/TempFolder.ts
index 7f574f22ef..a35ce55267 100644
--- a/packages/stryker/src/utils/TempFolder.ts
+++ b/packages/stryker/src/utils/TempFolder.ts
@@ -1,4 +1,4 @@
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import * as path from 'path';
 import * as mkdirp from 'mkdirp';
 import { getLogger } from 'stryker-api/logging';
@@ -41,8 +41,8 @@ export class TempFolder {
    */
   public copyFile(fromFilename: string, toFilename: string, instrumenter: NodeJS.ReadWriteStream | null): Promise<void> {
     return new Promise<void>((resolve, reject) => {
-      let readStream: NodeJS.ReadableStream = fs.createReadStream(fromFilename, { encoding: 'utf8' });
-      const writeStream = fs.createWriteStream(toFilename);
+      let readStream: NodeJS.ReadableStream = fsAsPromised.createReadStream(fromFilename, { encoding: 'utf8' });
+      const writeStream = fsAsPromised.createWriteStream(toFilename);
       readStream.on('error', reject);
       writeStream.on('error', reject);
       if (instrumenter) {
diff --git a/packages/stryker/src/utils/fileUtils.ts b/packages/stryker/src/utils/fileUtils.ts
index 502a156368..4387e74a00 100644
--- a/packages/stryker/src/utils/fileUtils.ts
+++ b/packages/stryker/src/utils/fileUtils.ts
@@ -1,8 +1,8 @@
-import * as fs from 'mz/fs';
 import * as path from 'path';
 import * as nodeGlob from 'glob';
 import * as mkdirp from 'mkdirp';
 import * as rimraf from 'rimraf';
+import { fsAsPromised } from '@stryker-mutator/util';
 
 export function glob(expression: string): Promise<string[]> {
   return new Promise<string[]>((resolve, reject) => {
@@ -18,7 +18,7 @@ export function deleteDir(dirToDelete: string): Promise<void> {
 
 export async function cleanFolder(folderName: string) {
   try {
-    await fs.lstat(folderName);
+    await fsAsPromised.lstat(folderName);
     await deleteDir(folderName);
     return mkdirp.sync(folderName);
   } catch (e) {
@@ -42,9 +42,9 @@ export function importModule(moduleName: string) {
  */
 export function writeFile(fileName: string, data: string | Buffer): Promise<void> {
   if (Buffer.isBuffer(data)) {
-    return fs.writeFile(fileName, data);
+    return fsAsPromised.writeFile(fileName, data);
   } else {
-    return fs.writeFile(fileName, data, 'utf8');
+    return fsAsPromised.writeFile(fileName, data, 'utf8');
   }
 }
 
@@ -54,7 +54,7 @@ export function writeFile(fileName: string, data: string | Buffer): Promise<void
  * @param from The thing you want to point from
  */
 export function symlinkJunction(to: string, from: string) {
-  return fs.symlink(to, from, 'junction');
+  return fsAsPromised.symlink(to, from, 'junction');
 }
 
 /**
@@ -65,8 +65,7 @@ export function symlinkJunction(to: string, from: string) {
 export async function findNodeModules(basePath: string): Promise<string | null> {
   basePath = path.resolve(basePath);
   const nodeModules = path.resolve(basePath, 'node_modules');
-  const exists = await fs.exists(nodeModules);
-  if (exists) {
+  if (await fsAsPromised.exists(nodeModules)) {
     return nodeModules;
   } else {
     const parent = path.dirname(basePath);
diff --git a/packages/stryker/test/integration/source-mapper/SourceMapperIT.ts b/packages/stryker/test/integration/source-mapper/SourceMapperIT.ts
index 26bf3147ca..07665becbc 100644
--- a/packages/stryker/test/integration/source-mapper/SourceMapperIT.ts
+++ b/packages/stryker/test/integration/source-mapper/SourceMapperIT.ts
@@ -1,8 +1,8 @@
-import * as fs from 'mz/fs';
 import * as path from 'path';
 import { File } from 'stryker-api/core';
 import { TranspiledSourceMapper } from '../../../src/transpiler/SourceMapper';
 import { expect } from 'chai';
+import { fsAsPromised } from '@stryker-mutator/util';
 
 function resolve(...filePart: string[]) {
   return path.resolve(__dirname, '..', '..', '..', 'testResources', 'source-mapper', ...filePart);
@@ -11,7 +11,7 @@ function resolve(...filePart: string[]) {
 function readFiles(...files: string[]): Promise<File[]> {
   return Promise.all(files
     .map(relative => resolve(relative))
-    .map(fileName => fs.readFile(fileName).then(content => new File(fileName, content))));
+    .map(fileName => fsAsPromised.readFile(fileName).then(content => new File(fileName, content))));
 }
 
 describe('Source mapper integration', function() {
diff --git a/packages/stryker/test/unit/PluginLoaderSpec.ts b/packages/stryker/test/unit/PluginLoaderSpec.ts
index 71ec1b8df4..7ef956eecd 100644
--- a/packages/stryker/test/unit/PluginLoaderSpec.ts
+++ b/packages/stryker/test/unit/PluginLoaderSpec.ts
@@ -1,5 +1,4 @@
 import * as path from 'path';
-import * as fs from 'mz/fs';
 import { Logger } from 'stryker-api/logging';
 import * as sinon from 'sinon';
 import { expect } from 'chai';
@@ -7,6 +6,7 @@ import * as fileUtils from '../../src/utils/fileUtils';
 import PluginLoader from '../../src/PluginLoader';
 import currentLogMock from '../helpers/logMock';
 import { Mock } from '../helpers/producers';
+import { fsAsPromised } from '@stryker-mutator/util';
 
 describe('PluginLoader', () => {
 
@@ -20,7 +20,7 @@ describe('PluginLoader', () => {
     log = currentLogMock();
     sandbox = sinon.createSandbox();
     importModuleStub = sandbox.stub(fileUtils, 'importModule');
-    pluginDirectoryReadMock = sandbox.stub(fs, 'readdirSync');
+    pluginDirectoryReadMock = sandbox.stub(fsAsPromised, 'readdirSync');
   });
 
   describe('without wildcards', () => {
diff --git a/packages/stryker/test/unit/initializer/StrykerInitializerSpec.ts b/packages/stryker/test/unit/initializer/StrykerInitializerSpec.ts
index 530d1b523f..cc2c0581e2 100644
--- a/packages/stryker/test/unit/initializer/StrykerInitializerSpec.ts
+++ b/packages/stryker/test/unit/initializer/StrykerInitializerSpec.ts
@@ -1,7 +1,7 @@
 import * as child from 'child_process';
-import * as fs from 'mz/fs';
 import * as sinon from 'sinon';
 import { Logger } from 'stryker-api/logging';
+import { fsAsPromised } from '@stryker-mutator/util';
 import { expect } from 'chai';
 import * as inquirer from 'inquirer';
 import StrykerInitializer from '../../../src/initializer/StrykerInitializer';
@@ -25,8 +25,8 @@ describe('StrykerInitializer', () => {
     out = sandbox.stub();
     inquirerPrompt = sandbox.stub(inquirer, 'prompt');
     childExecSync = sandbox.stub(child, 'execSync');
-    fsWriteFile = sandbox.stub(fs, 'writeFile');
-    fsExistsSync = sandbox.stub(fs, 'existsSync');
+    fsWriteFile = sandbox.stub(fsAsPromised, 'writeFile');
+    fsExistsSync = sandbox.stub(fsAsPromised, 'existsSync');
     restClientSearchGet = sandbox.stub();
     restClientPackageGet = sandbox.stub();
     sandbox.stub(restClient, 'RestClient')
@@ -120,7 +120,7 @@ describe('StrykerInitializer', () => {
       await sut.initialize();
       expect(inquirerPrompt).to.have.been.callCount(6);
       expect(out).to.have.been.calledWith('OK, downgrading coverageAnalysis to "all"');
-      expect(fs.writeFile).to.have.been.calledWith('stryker.conf.js', sinon.match('coverageAnalysis: "all"'));
+      expect(fsAsPromised.writeFile).to.have.been.calledWith('stryker.conf.js', sinon.match('coverageAnalysis: "all"'));
     });
 
     it('should install any additional dependencies', async () => {
@@ -148,7 +148,7 @@ describe('StrykerInitializer', () => {
         transpilers: ['webpack']
       });
       await sut.initialize();
-      expect(fs.writeFile).to.have.been.calledWith('stryker.conf.js', sinon.match('testRunner: "awesome"')
+      expect(fsAsPromised.writeFile).to.have.been.calledWith('stryker.conf.js', sinon.match('testRunner: "awesome"')
         .and(sinon.match('testFramework: "awesome"'))
         .and(sinon.match('packageManager: "npm"'))
         .and(sinon.match('coverageAnalysis: "perTest"'))
@@ -166,8 +166,8 @@ describe('StrykerInitializer', () => {
         transpilers: ['webpack']
       });
       await sut.initialize();
-      expect(fs.writeFile).to.have.been.calledWith('stryker.conf.js', sinon.match('someOtherSetting: "enabled"'));
-      expect(fs.writeFile).to.have.been.calledWith('stryker.conf.js', sinon.match('files: []'));
+      expect(fsAsPromised.writeFile).to.have.been.calledWith('stryker.conf.js', sinon.match('someOtherSetting: "enabled"'));
+      expect(fsAsPromised.writeFile).to.have.been.calledWith('stryker.conf.js', sinon.match('files: []'));
     });
 
     describe('but no testFramework can be found that supports the testRunner', () => {
@@ -190,7 +190,7 @@ describe('StrykerInitializer', () => {
         await sut.initialize();
 
         expect(out).to.have.been.calledWith('No stryker test framework plugin found that is compatible with ghost, downgrading coverageAnalysis to "all"');
-        expect(fs.writeFile).to.have.been.calledWith('stryker.conf.js', sinon.match('coverageAnalysis: "all"'));
+        expect(fsAsPromised.writeFile).to.have.been.calledWith('stryker.conf.js', sinon.match('coverageAnalysis: "all"'));
       });
     });
 
@@ -221,7 +221,7 @@ describe('StrykerInitializer', () => {
       await sut.initialize();
 
       expect(out).to.have.been.calledWith('An error occurred during installation, please try it yourself: "npm i --save-dev stryker-api stryker-ghost-runner"');
-      expect(fs.writeFile).to.have.been.called;
+      expect(fsAsPromised.writeFile).to.have.been.called;
     });
   });
 
@@ -243,7 +243,7 @@ describe('StrykerInitializer', () => {
 
       expect(log.error).to.have.been.calledWith('Unable to reach https://api.npms.io (for query /v2/search?q=keywords:stryker-test-runner). Please check your internet connection.');
       expect(out).to.have.been.calledWith('Unable to select a test runner. You will need to configure it manually.');
-      expect(fs.writeFile).to.have.been.called;
+      expect(fsAsPromised.writeFile).to.have.been.called;
     });
 
     it('should log error and continue when fetching test frameworks', async () => {
@@ -264,7 +264,7 @@ describe('StrykerInitializer', () => {
 
       expect(log.error).to.have.been.calledWith('Unable to reach https://api.npms.io (for query /v2/search?q=keywords:stryker-test-framework). Please check your internet connection.');
       expect(out).to.have.been.calledWith('No stryker test framework plugin found that is compatible with awesome, downgrading coverageAnalysis to "all"');
-      expect(fs.writeFile).to.have.been.called;
+      expect(fsAsPromised.writeFile).to.have.been.called;
     });
 
     it('should log error and continue when fetching mutators', async () => {
@@ -285,7 +285,7 @@ describe('StrykerInitializer', () => {
 
       expect(log.error).to.have.been.calledWith('Unable to reach https://api.npms.io (for query /v2/search?q=keywords:stryker-mutator). Please check your internet connection.');
       expect(out).to.have.been.calledWith('Unable to select a mutator. You will need to configure it manually.');
-      expect(fs.writeFile).to.have.been.called;
+      expect(fsAsPromised.writeFile).to.have.been.called;
     });
 
     it('should log error and continue when fetching transpilers', async () => {
@@ -305,7 +305,7 @@ describe('StrykerInitializer', () => {
 
       expect(log.error).to.have.been.calledWith('Unable to reach https://api.npms.io (for query /v2/search?q=keywords:stryker-transpiler). Please check your internet connection.');
       expect(out).to.have.been.calledWith('Unable to select transpilers. You will need to configure it manually, if you want to use any.');
-      expect(fs.writeFile).to.have.been.called;
+      expect(fsAsPromised.writeFile).to.have.been.called;
     });
 
     it('should log error and continue when fetching stryker reporters', async () => {
@@ -325,7 +325,7 @@ describe('StrykerInitializer', () => {
       await sut.initialize();
 
       expect(log.error).to.have.been.calledWith('Unable to reach https://api.npms.io (for query /v2/search?q=keywords:stryker-reporter). Please check your internet connection.');
-      expect(fs.writeFile).to.have.been.called;
+      expect(fsAsPromised.writeFile).to.have.been.called;
     });
 
     it('should log warning and continue when fetching custom config', async () => {
@@ -345,7 +345,7 @@ describe('StrykerInitializer', () => {
       await sut.initialize();
 
       expect(log.warn).to.have.been.calledWith('Could not fetch additional initialization config for dependency stryker-awesome-runner. You might need to configure it manually');
-      expect(fs.writeFile).to.have.been.called;
+      expect(fsAsPromised.writeFile).to.have.been.called;
     });
 
   });
diff --git a/packages/stryker/test/unit/input/InputFileResolverSpec.ts b/packages/stryker/test/unit/input/InputFileResolverSpec.ts
index 9280e9b2c3..8fee03df73 100644
--- a/packages/stryker/test/unit/input/InputFileResolverSpec.ts
+++ b/packages/stryker/test/unit/input/InputFileResolverSpec.ts
@@ -1,7 +1,6 @@
 import * as path from 'path';
 import { expect } from 'chai';
-import * as fs from 'mz/fs';
-import * as childProcess from 'mz/child_process';
+import { childProcessAsPromised } from '@stryker-mutator/util';
 import { Logger } from 'stryker-api/logging';
 import { File } from 'stryker-api/core';
 import { SourceFile } from 'stryker-api/report';
@@ -12,6 +11,7 @@ import currentLogMock from '../../helpers/logMock';
 import BroadcastReporter from '../../../src/reporters/BroadcastReporter';
 import { Mock, mock, createFileNotFoundError } from '../../helpers/producers';
 import { errorToString, normalizeWhiteSpaces } from '../../../src/utils/objectUtils';
+import { fsAsPromised } from '@stryker-mutator/util';
 
 const files = (...namesWithContent: [string, string][]): File[] =>
   namesWithContent.map((nameAndContent): File => new File(
@@ -31,7 +31,7 @@ describe('InputFileResolver', () => {
     log = currentLogMock();
     reporter = mock(BroadcastReporter);
     globStub = sandbox.stub(fileUtils, 'glob');
-    readFileStub = sandbox.stub(fs, 'readFile')
+    readFileStub = sandbox.stub(fsAsPromised, 'readFile')
       .withArgs(sinon.match.string).resolves(Buffer.from('')) // fallback
       .withArgs(sinon.match.string).resolves(Buffer.from('')) // fallback
       .withArgs(sinon.match('file1')).resolves(Buffer.from('file 1 content'))
@@ -47,15 +47,17 @@ describe('InputFileResolver', () => {
     globStub.withArgs('file3').resolves(['/file3.js']);
     globStub.withArgs('file*').resolves(['/file1.js', '/file2.js', '/file3.js']);
     globStub.resolves([]); // default
-    childProcessExecStub = sandbox.stub(childProcess, 'exec');
+    childProcessExecStub = sandbox.stub(childProcessAsPromised, 'exec');
   });
 
   it('should use git to identify files if files array is missing', async () => {
     sut = new InputFileResolver([], undefined, reporter);
-    childProcessExecStub.resolves([Buffer.from(`
+    childProcessExecStub.resolves({
+      stdout: Buffer.from(`
     file1.js
     foo/bar/baz.ts
-    `)]);
+    `)
+    });
     const result = await sut.resolve();
     expect(childProcessExecStub).calledWith('git ls-files --others --exclude-standard --cached --exclude .stryker-tmp',
       { maxBuffer: 10 * 1000 * 1024 });
@@ -81,9 +83,11 @@ describe('InputFileResolver', () => {
 
   it('should be able to handled deleted files reported by `git ls-files`', async () => {
     sut = new InputFileResolver([], undefined, reporter);
-    childProcessExecStub.resolves([Buffer.from(`
+    childProcessExecStub.resolves({
+      stdout: Buffer.from(`
       deleted/file.js
-    `)]);
+    `)
+    });
     const fileNotFoundError = createFileNotFoundError();
     readFileStub.withArgs('deleted/file.js').rejects(fileNotFoundError);
     const result = await sut.resolve();
diff --git a/packages/stryker/test/unit/reporters/EventRecorderReporterSpec.ts b/packages/stryker/test/unit/reporters/EventRecorderReporterSpec.ts
index f2cb4ce56d..bbbd898c44 100644
--- a/packages/stryker/test/unit/reporters/EventRecorderReporterSpec.ts
+++ b/packages/stryker/test/unit/reporters/EventRecorderReporterSpec.ts
@@ -1,12 +1,12 @@
 import { expect } from 'chai';
 import * as sinon from 'sinon';
-import * as fs from 'mz/fs';
 import { Reporter } from 'stryker-api/report';
 import EventRecorderReporter from '../../../src/reporters/EventRecorderReporter';
 import * as fileUtils from '../../../src/utils/fileUtils';
 import currentLogMock from '../../helpers/logMock';
 import StrictReporter from '../../../src/reporters/StrictReporter';
 import { ALL_REPORTER_EVENTS } from '../../helpers/producers';
+import { fsAsPromised } from '@stryker-mutator/util';
 
 describe('EventRecorderReporter', () => {
 
@@ -18,7 +18,7 @@ describe('EventRecorderReporter', () => {
   beforeEach(() => {
     sandbox = sinon.createSandbox();
     cleanFolderStub = sandbox.stub(fileUtils, 'cleanFolder');
-    writeFileStub = sandbox.stub(fs, 'writeFile');
+    writeFileStub = sandbox.stub(fsAsPromised, 'writeFile');
   });
 
   afterEach(() => {
@@ -63,7 +63,7 @@ describe('EventRecorderReporter', () => {
 
           describe('when writeFile is successful', () => {
             arrange();
-            it('should writeFile', () => expect(fs.writeFile).to.have.been.calledWith(sinon.match(RegExp(`.*0000\\d-${eventName}\\.json`)), JSON.stringify(expected)));
+            it('should writeFile', () => expect(fsAsPromised.writeFile).to.have.been.calledWith(sinon.match(RegExp(`.*0000\\d-${eventName}\\.json`)), JSON.stringify(expected)));
           });
         });
       };
diff --git a/packages/stryker/test/unit/utils/TempFolderSpec.ts b/packages/stryker/test/unit/utils/TempFolderSpec.ts
index ee8a341267..8c19a44a67 100644
--- a/packages/stryker/test/unit/utils/TempFolderSpec.ts
+++ b/packages/stryker/test/unit/utils/TempFolderSpec.ts
@@ -1,7 +1,7 @@
 import * as sinon from 'sinon';
 import { expect } from 'chai';
 import * as mkdirp from 'mkdirp';
-import * as fs from 'mz/fs';
+import { fsAsPromised } from '@stryker-mutator/util';
 import { TempFolder } from '../../../src/utils/TempFolder';
 import * as fileUtils from '../../../src/utils/fileUtils';
 
@@ -16,7 +16,7 @@ describe('TempFolder', () => {
     sandbox = sinon.createSandbox();
 
     sandbox.stub(mkdirp, 'sync');
-    sandbox.stub(fs, 'writeFile');
+    sandbox.stub(fsAsPromised, 'writeFile');
     deleteDirStub = sandbox.stub(fileUtils, 'deleteDir');
     cwdStub = sandbox.stub(process, 'cwd');
     cwdStub.returns(mockCwd);
diff --git a/packages/stryker/test/unit/utils/fileUtilsSpec.ts b/packages/stryker/test/unit/utils/fileUtilsSpec.ts
index 10cf144b36..e0448a2f01 100644
--- a/packages/stryker/test/unit/utils/fileUtilsSpec.ts
+++ b/packages/stryker/test/unit/utils/fileUtilsSpec.ts
@@ -1,29 +1,29 @@
+import * as path from 'path';
 import { expect } from 'chai';
+import { fsAsPromised } from '@stryker-mutator/util';
 import * as fileUtils from '../../../src/utils/fileUtils';
-import * as fs from 'mz/fs';
-import * as path from 'path';
 
 describe('fileUtils', () => {
 
   let existsStub: sinon.SinonStub;
 
   beforeEach(() => {
-    sandbox.stub(fs, 'writeFile');
-    sandbox.stub(fs, 'symlink');
-    existsStub = sandbox.stub(fs, 'exists');
+    sandbox.stub(fsAsPromised, 'writeFile');
+    sandbox.stub(fsAsPromised, 'symlink');
+    existsStub = sandbox.stub(fsAsPromised, 'exists');
   });
 
   describe('writeFile', () => {
     it('should call fs.writeFile', () => {
       fileUtils.writeFile('filename', 'data');
-      expect(fs.writeFile).calledWith('filename', 'data', 'utf8');
+      expect(fsAsPromised.writeFile).calledWith('filename', 'data', 'utf8');
     });
   });
 
   describe('symlinkJunction', () => {
     it('should call fs.symlink', async () => {
       await fileUtils.symlinkJunction('a', 'b');
-      expect(fs.symlink).calledWith('a', 'b', 'junction');
+      expect(fsAsPromised.symlink).calledWith('a', 'b', 'junction');
     });
   });
 
diff --git a/workspace.code-workspace b/workspace.code-workspace
index 1b0a4aeab3..62a01d09a9 100644
--- a/workspace.code-workspace
+++ b/workspace.code-workspace
@@ -48,6 +48,9 @@
 		{
 			"path": "packages/stryker-webpack-transpiler"
 		},
+		{
+			"path": "packages/stryker-util"
+		},
 		{
 			"path": "integrationTest"
 		}
@@ -66,4 +69,4 @@
 			}
 		}
 	}
-}
\ No newline at end of file
+}