diff --git a/gulpfile.babel.js b/gulpfile.babel.js
index 03b25a6..2d6feea 100644
--- a/gulpfile.babel.js
+++ b/gulpfile.babel.js
@@ -13,6 +13,11 @@ import fs           from 'fs'
 import yaml         from 'js-yaml'
 import request      from 'request'
 
+// required to get our mix of old and ES6+ js to work with ugify-js 3
+import uglifyjs     from 'uglify-es'
+import composer     from 'gulp-uglify/composer'
+const minify = composer(uglifyjs, console)
+
 // get all the configs: `pkg` and `site`
 import pkg from './package.json'
 const site = yaml.safeLoad(fs.readFileSync('./_config.yml'))
@@ -196,7 +201,7 @@ export const js = () =>
     .pipe($.include({
         includePaths: ['node_modules', SRC + '_assets/javascripts']
     })).on('error', onError)
-    .pipe($.if(isProduction || isStaging, $.uglify())).on('error', onError)
+    .pipe($.if(isProduction || isStaging, minify())).on('error', onError)
     .pipe($.if(!(isProduction || isStaging), $.sourcemaps.write()))
     .pipe($.if(isProduction || isStaging, $.header(BANNER, { pkg: pkg })))
     .pipe($.rename({suffix: '.min'}))
diff --git a/package.json b/package.json
index e65cdb8..4ba350e 100644
--- a/package.json
+++ b/package.json
@@ -66,7 +66,8 @@
     "gulp-uglify": "^3.0.0",
     "gulp-util": "^3.0.6",
     "js-yaml": "^3.8.3",
-    "request": "^2.81.0"
+    "request": "^2.81.0",
+    "uglify-es": "^3.0.13"
   },
   "engines": {
     "node": ">=7.0.0"