diff --git a/lib/terser_wrapper.js b/lib/terser_wrapper.js
index e760334..ba7a6fa 100644
--- a/lib/terser_wrapper.js
+++ b/lib/terser_wrapper.js
@@ -1,6 +1,8 @@
 // Set source-map.js sourceMap to terser.js MOZ_SourceMap
 MOZ_SourceMap = sourceMap;
 
+var global = global || {};
+
 function comments(option) {
   if (Object.prototype.toString.call(option) === '[object Array]') {
     return new RegExp(option[0], option[1]);