diff --git a/README.md b/README.md
index ba3429b05b..88fb71c5e9 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,8 @@ Reactive libraries for Angular
 
 ## Support
 
-[![Join the chat at https://gitter.im/ngrx/store](https://badges.gitter.im/ngrx/store.svg)](https://gitter.im/ngrx/store?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Join the chat at https://gitter.im/ngrx/store](https://badges.gitter.im/ngrx/store.svg)](https://gitter.im/ngrx/store?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)[![Commitizen friendly](https://img.shields.io/badge/commitizen-friendly-brightgreen.svg)](http://commitizen.github.io/cz-cli/)
+
 
 ## Packages
 
diff --git a/build/tasks.ts b/build/tasks.ts
index 98050171ce..870906e685 100644
--- a/build/tasks.ts
+++ b/build/tasks.ts
@@ -5,10 +5,8 @@ import * as util from './util';
  * Cleans the top level dist folder. All npm-ready packages are created
  * in the dist folder.
  */
-export async function removeDistFolder(config: Config) {
-  const args = ['./dist'];
-
-  return await util.exec('rimraf', args);
+export function removeDistFolder(config: Config) {
+  return util.exec('rimraf', ['./dist']);
 }
 
 /**
@@ -22,8 +20,8 @@ export async function compilePackagesWithNgc(config: Config) {
   const testPkgs = util.getTestingPackages(config);
 
   await _compilePackagesWithNgc(storePkg);
-  await mapPackages(restPkgs, _compilePackagesWithNgc);
-  await mapPackages(testPkgs, _compilePackagesWithNgc);
+  await mapAsync(restPkgs, _compilePackagesWithNgc);
+  await mapAsync(testPkgs, _compilePackagesWithNgc);
 }
 
 async function _compilePackagesWithNgc(pkg: string) {
@@ -32,8 +30,10 @@ async function _compilePackagesWithNgc(pkg: string) {
   const entryTypeDefinition = `export * from './${pkg}/index';`;
   const entryMetadata = `{"__symbolic":"module","version":3,"metadata":{},"exports":[{"from":"./${pkg}/index"}]}`;
 
-  util.writeFile(`./dist/packages/${pkg}.d.ts`, entryTypeDefinition);
-  util.writeFile(`./dist/packages/${pkg}.metadata.json`, entryMetadata);
+  await Promise.all([
+    util.writeFile(`./dist/packages/${pkg}.d.ts`, entryTypeDefinition),
+    util.writeFile(`./dist/packages/${pkg}.metadata.json`, entryMetadata),
+  ]);
 }
 
 /**
@@ -43,7 +43,7 @@ async function _compilePackagesWithNgc(pkg: string) {
 export async function bundleFesms(config: Config) {
   const pkgs = util.getAllPackages(config);
 
-  await mapPackages(pkgs, async pkg => {
+  await mapAsync(pkgs, async pkg => {
     const topLevelName = util.getTopLevelName(pkg);
 
     await util.exec('rollup', [
@@ -64,14 +64,13 @@ export async function downLevelFesmsToES5(config: Config) {
   const packages = util.getAllPackages(config);
   const tscArgs = ['--target es5', '--module es2015', '--noLib', '--sourceMap'];
 
-  await mapPackages(packages, async pkg => {
+  await mapAsync(packages, async pkg => {
     const topLevelName = util.getTopLevelName(pkg);
 
     const file = `./dist/${topLevelName}/${config.scope}/${pkg}.js`;
     const target = `./dist/${topLevelName}/${config.scope}/${pkg}.es5.ts`;
 
-    util.copy(file, target);
-
+    await util.copy(file, target);
     await util.ignoreErrors(util.exec('tsc', [target, ...tscArgs]));
     await util.mapSources(target.replace('.ts', '.js'));
     await util.remove(target);
@@ -84,7 +83,7 @@ export async function downLevelFesmsToES5(config: Config) {
  * Re-runs Rollup on the downleveled ES5 to produce a UMD bundle
  */
 export async function createUmdBundles(config: Config) {
-  await mapPackages(util.getAllPackages(config), async pkg => {
+  await mapAsync(util.getAllPackages(config), async pkg => {
     const topLevelName = util.getTopLevelName(pkg);
     const destinationName = util.getDestinationName(pkg);
 
@@ -106,9 +105,7 @@ export async function cleanTypeScriptFiles(config: Config) {
   const dtsFilesFlob = './dist/packages/**/*.d.ts';
   const filesToRemove = await util.getListOfFiles(tsFilesGlob, dtsFilesFlob);
 
-  for (let file of filesToRemove) {
-    util.remove(file);
-  }
+  await mapAsync(filesToRemove, util.remove);
 }
 
 /**
@@ -116,16 +113,17 @@ export async function cleanTypeScriptFiles(config: Config) {
  * of the package.
  */
 export async function renamePackageEntryFiles(config: Config) {
-  await mapPackages(util.getAllPackages(config), async pkg => {
+  await mapAsync(util.getAllPackages(config), async pkg => {
     const bottomLevelName = util.getBottomLevelName(pkg);
 
     const files = await util.getListOfFiles(`./dist/packages/${pkg}/index.**`);
 
-    for (let file of files) {
+    await mapAsync(files, async file => {
       const target = file.replace('index', bottomLevelName);
-      util.copy(file, target);
-      util.remove(file);
-    }
+
+      await util.copy(file, target);
+      await util.remove(file);
+    });
   });
 }
 
@@ -150,10 +148,10 @@ export async function copyTypeDefinitionFiles(config: Config) {
     `./dist/packages/?(${packages.join('|')})/**/*`
   );
 
-  for (let file of files) {
+  await mapAsync(files, async file => {
     const target = file.replace('packages/', '');
-    util.copy(file, target);
-  }
+    await util.copy(file, target);
+  });
 
   await util.removeRecursively(`./dist/packages/?(${packages.join('|')})`);
 }
@@ -164,7 +162,7 @@ export async function copyTypeDefinitionFiles(config: Config) {
 export async function minifyUmdBundles(config: Config) {
   const uglifyArgs = ['-c', '-m', '--screw-ie8', '--comments'];
 
-  await mapPackages(util.getAllPackages(config), async pkg => {
+  await mapAsync(util.getAllPackages(config), async pkg => {
     const topLevelName = util.getTopLevelName(pkg);
     const destinationName = util.getDestinationName(pkg);
     const file = `./dist/${topLevelName}/bundles/${destinationName}.umd.js`;
@@ -187,24 +185,26 @@ export async function minifyUmdBundles(config: Config) {
 export async function copyDocs(config: Config) {
   const packages = util.getTopLevelPackages(config);
 
-  for (let pkg of packages) {
+  await mapAsync(packages, async pkg => {
     const source = `./modules/${pkg}`;
     const target = `./dist/${pkg}`;
 
-    util.copy(`${source}/README.md`, `${target}/README.md`);
-    util.copy('./LICENSE', `${target}/LICENSE`);
-  }
+    await Promise.all([
+      util.copy(`${source}/README.md`, `${target}/README.md`),
+      util.copy('./LICENSE', `${target}/LICENSE`),
+    ]);
+  });
 }
 
 export async function copyPackageJsonFiles(config: Config) {
   const packages = util.getAllPackages(config);
 
-  for (let pkg of packages) {
+  await mapAsync(packages, async pkg => {
     const source = `./modules/${pkg}`;
     const target = `./dist/${pkg}`;
 
-    util.copy(`${source}/package.json`, `${target}/package.json`);
-  }
+    await util.copy(`${source}/package.json`, `${target}/package.json`);
+  });
 }
 
 /**
@@ -254,9 +254,9 @@ export async function publishToRepo(config: Config) {
   }
 }
 
-export function mapPackages(
-  packages: string[],
-  mapFn: (pkg: string, i: number) => Promise<any>
+export function mapAsync<T>(
+  list: T[],
+  mapFn: (v: T, i: number) => Promise<any>
 ) {
-  return Promise.all(packages.map(mapFn));
+  return Promise.all(list.map(mapFn));
 }
diff --git a/build/util.ts b/build/util.ts
index 8efed0f41d..b26526c4ef 100644
--- a/build/util.ts
+++ b/build/util.ts
@@ -6,24 +6,35 @@ import * as path from 'path';
 import * as rimraf from 'rimraf';
 import { Config } from './config';
 
-export function copy(target: string, destination: string) {
-  fsExtra.copySync(target, destination);
-}
-
-export function remove(target: string) {
-  fsExtra.removeSync(target);
-}
+export type RunnerFn = (config: Config) => Promise<any>;
+export type TaskDef = [string, RunnerFn];
+export type BaseFn = (command: string) => string;
 
-export function writeFile(target: string, contents: string) {
-  fs.writeFileSync(target, contents);
+export function copy(target: string, destination: string): Promise<void> {
+  return new Promise((resolve, reject) => {
+    fsExtra.copy(target, destination, err => {
+      if (err) return reject(err);
+      resolve();
+    });
+  });
 }
 
-export function mkdir(target: string) {
-  fs.mkdirSync(target);
+export function remove(target: string): Promise<void> {
+  return new Promise((resolve, reject) => {
+    fsExtra.remove(target, err => {
+      if (err) return reject(err);
+      resolve();
+    });
+  });
 }
 
-export function rmdir(target: string) {
-  fs.rmdirSync(target);
+export function writeFile(target: string, contents: string) {
+  return new Promise((resolve, reject) => {
+    fs.writeFile(target, contents, err => {
+      if (err) return reject(err);
+      resolve();
+    });
+  });
 }
 
 export function getListOfFiles(
@@ -58,10 +69,10 @@ export function removeRecursively(glob: string) {
 export function exec(
   command: string,
   args: string[],
-  base: (command: string) => string = fromNpm
+  base: BaseFn = fromNpm
 ): Promise<string> {
   return new Promise((resolve, reject) => {
-    cp.exec(base(command) + ' ' + args.join(' '), (err, stdout, stderr) => {
+    cp.exec(base(command) + ' ' + args.join(' '), (err, stdout) => {
       if (err) {
         return reject(err);
       }
@@ -76,37 +87,25 @@ export function cmd(command: string, args: string[]): Promise<string> {
 }
 
 export function git(args: string[]): Promise<string> {
-  return exec('git', args, (command: string) => command);
+  return cmd('git', args);
 }
 
-export async function ignoreErrors<T>(promise: Promise<T>): Promise<T | null> {
-  try {
-    const result = await promise;
-    return result;
-  } catch (err) {
-    return null;
-  }
+export function ignoreErrors<T>(promise: Promise<T>): Promise<T | null> {
+  return promise.catch(() => null);
 }
 
 export function fromNpm(command: string) {
-  return path.normalize(`./node_modules/.bin/${command}`);
+  return baseDir(`./node_modules/.bin/${command}`);
 }
 
 export function getPackageFilePath(pkg: string, filename: string) {
-  return path.resolve(process.cwd(), `./modules/${pkg}/${filename}`);
+  return baseDir(`./modules/${pkg}/${filename}`);
 }
 
 const sorcery = require('sorcery');
-export function mapSources(file: string) {
-  return new Promise((resolve, reject) => {
-    sorcery
-      .load(file)
-      .then((chain: any) => {
-        chain.write();
-        resolve();
-      })
-      .catch(reject);
-  });
+export async function mapSources(file: string) {
+  const chain = await sorcery.load(file);
+  chain.write();
 }
 
 const ora = require('ora');
@@ -126,9 +125,7 @@ async function runTask(name: string, taskFn: () => Promise<any>) {
   }
 }
 
-export function createBuilder(
-  tasks: [string, (config: Config) => Promise<any>][]
-) {
+export function createBuilder(tasks: TaskDef[]) {
   return async function(config: Config) {
     for (let [name, runner] of tasks) {
       await runTask(name, () => runner(config));
@@ -157,12 +154,12 @@ export function getTestingPackages(config: Config) {
 }
 
 export function getAllPackages(config: Config) {
-  return flatMap(config.packages, packageDescription => {
-    if (packageDescription.hasTestingModule) {
-      return [packageDescription.name, `${packageDescription.name}/testing`];
+  return flatMap(config.packages, ({ name, hasTestingModule }) => {
+    if (hasTestingModule) {
+      return [name, `${name}/testing`];
     }
 
-    return [packageDescription.name];
+    return [name];
   });
 }
 
@@ -177,3 +174,7 @@ export function getTopLevelName(packageName: string) {
 export function getBottomLevelName(packageName: string) {
   return packageName.includes('/testing') ? 'testing' : packageName;
 }
+
+export function baseDir(...dirs: string[]): string {
+  return path.resolve(__dirname, '../', ...dirs);
+}
diff --git a/circle.yml b/circle.yml
index 04e46274fe..f6cf91ac6d 100644
--- a/circle.yml
+++ b/circle.yml
@@ -1,11 +1,22 @@
 machine:
+  environment:
+    PATH: "${PATH}:${HOME}/${CIRCLE_PROJECT_REPONAME}/node_modules/.bin"
   node:
     version: 6.9.5
-test:
+
+dependencies:
+  pre:
+    - curl -o- -L https://yarnpkg.com/install.sh | bash -s -- --version 0.28.1
+  cache_directories:
+    - ~/.cache/yarn
   override:
-    - npm install -g yarn
+    - yarn
     - yarn run bootstrap -- --concurrency=1
+
+test:
+  override:
     - yarn run ci
+
 deployment:
   builds:
     owner: ngrx