diff --git a/lib/common/uglify.options.js b/lib/common/uglify.options.js
index 64aebf6f5..e82596110 100644
--- a/lib/common/uglify.options.js
+++ b/lib/common/uglify.options.js
@@ -8,6 +8,7 @@
  */
 module.exports = {
   'compress': {
+    'collapse_vars': true,
     'negate_iife': false,
     'pure_getters': true,
     'unsafe': true,