diff --git a/lib/utils.js b/lib/utils.js
index 76306919..ecb74a73 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -1,4 +1,3 @@
-/***********************************************************************
 
   A JavaScript tokenizer / parser / beautifier / compressor.
   https://github.com/mishoo/UglifyJS2
@@ -229,7 +228,7 @@ function set_intersection(a, b) {
 // this function is taken from Acorn [1], written by Marijn Haverbeke
 // [1] https://github.com/marijnh/acorn
 function makePredicate(words) {
-    if (!(words instanceof Array)) words = words.split(" ");
+    if (!(words instanceof Array)) words = words.toString().split(" ");
     var f = "", cats = [];
     out: for (var i = 0; i < words.length; ++i) {
         for (var j = 0; j < cats.length; ++j)