diff --git a/lib/output.js b/lib/output.js
index 777ee3e..32b2c75 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -8,6 +8,17 @@ var extend = require('./utils').extend;
 var fromFileURL = require('./utils').fromFileURL;
 var toFileURL = require('./utils').toFileURL;
 
+// Ugly hack (no pun intended) to get around uglify-js strange code loading
+// and export system, and the fact that their SourceMap wrapper is no longer
+// exported in uglify-js@3 / uglify-es
+var UglifySourceMap = new Function('MOZ_SourceMap', function() {
+  var code = ['uglify-es/lib/utils.js', 'uglify-es/lib/sourcemap.js'].map(function(file) {
+    return fs.readFileSync(require.resolve(file), 'utf8');
+  });
+  code.push('return SourceMap;');
+  return code.join('\n');
+}())(require('source-map'));
+
 function countLines(str) {
   return str.split(/\r\n|\r|\n/).length;
 }
@@ -72,36 +83,30 @@ function createOutput(outFile, outputs, basePath, sourceMaps, sourceMapContents)
 }
 
 function minify(output, fileName, mangle, uglifyOpts) {
-  var uglify = require('uglify-js');
+  var uglify = require('uglify-es');
+  var files = {};
+  files[fileName] = output.source;
   var ast;
   try{
-    ast = uglify.parse(output.source, { filename: fileName });
+    ast = uglify.minify(files, {
+      parse: {},
+      compress: false,
+      mangle: mangle,
+      output: { ast: true, code: false }
+    }).ast;
   } catch(e){
     throw new Error(e);
   }
-  ast.figure_out_scope();
-  
-  ast = ast.transform(uglify.Compressor(uglifyOpts.compress));
-  ast.figure_out_scope();
-  if (mangle !== false)
-    ast.mangle_names();
 
   var sourceMap;
   if (output.sourceMap) {
     if (typeof output.sourceMap === 'string')
       output.sourceMap = JSON.parse(output.sourceMap);
 
-    var sourceMapIn = output.sourceMap;
-    sourceMap = uglify.SourceMap({
+    sourceMap = UglifySourceMap({
       file: fileName,
-      orig: sourceMapIn
+      orig: output.sourceMap
     });
-
-    if (uglifyOpts.sourceMapIncludeSources && sourceMapIn && Array.isArray(sourceMapIn.sourcesContent)) {
-      sourceMapIn.sourcesContent.forEach(function(content, idx) {
-        sourceMap.get().setSourceContent(sourceMapIn.sources[idx], content);
-      });
-    }
   }
 
   var outputOptions = uglifyOpts.beautify;
diff --git a/package.json b/package.json
index 14e7360..7aba5a1 100644
--- a/package.json
+++ b/package.json
@@ -20,7 +20,7 @@
     "source-map": "^0.5.3",
     "systemjs": "^0.19.46",
     "traceur": "0.0.105",
-    "uglify-js": "^2.6.1"
+    "uglify-es": "^3.3.9"
   },
   "devDependencies": {
     "babel": "^5.8.38",
diff --git a/test/test-sfx.html b/test/test-sfx.html
index 36f4f84..2374570 100644
--- a/test/test-sfx.html
+++ b/test/test-sfx.html
@@ -6,13 +6,12 @@
     <div id="mocha">
   <script>
     window.$ = { jquery: 1 };
+    window.DEBUG = false;
   </script>
   <script src="output/sfx.js"></script>
   <script>
     mocha.setup('tdd');
 
-    DEBUG = false;
-
     function assert(assertion, msg) {
       if (!assertion)
         throw new Error(msg || 'Assertion failed');