diff --git a/gulpfile.js b/gulpfile.js
index 0015aaa60..055ec7899 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -7,6 +7,7 @@ var gulp = require('gulp')
 var babel = require('gulp-babel')
 var coffee = require('gulp-coffee')
 var plumber = require('gulp-plumber')
+var rimraf = require('rimraf')
 var sourceMaps = require('gulp-sourcemaps')
 var watch = require('gulp-watch')
 
@@ -38,6 +39,10 @@ function src (patterns) {
 
 // ===================================================================
 
+gulp.task(function clean (cb) {
+  rimraf(DIST_DIR, cb)
+})
+
 gulp.task(function buildCoffee () {
   return src('**/*.coffee')
     .pipe(sourceMaps.init())
@@ -62,4 +67,4 @@ gulp.task(function buildEs6 () {
 
 // ===================================================================
 
-gulp.task('build', gulp.parallel('buildCoffee', 'buildEs6'))
+gulp.task('build', gulp.series('clean', gulp.parallel('buildCoffee', 'buildEs6')))
diff --git a/package.json b/package.json
index 7e05d4a6f..8d829aae9 100644
--- a/package.json
+++ b/package.json
@@ -122,6 +122,7 @@
     "mocha": "^2.2.1",
     "must": "^0.13.1",
     "nyc": "^6.4.2",
+    "rimraf": "^2.5.2",
     "sinon": "^1.14.1",
     "standard": "^7.0.0"
   },