diff --git a/lib/string.js b/lib/string.js
index af5754d..a58a3ac 100644
--- a/lib/string.js
+++ b/lib/string.js
@@ -446,7 +446,7 @@ string.js - Copyright (C) 2012-2013, JP Richardson <jprichardson@gmail.com>
       return (template+pruneStr).length > str.length ? new S(str) : new S(str.slice(0, template.length)+pruneStr);
     },
 
-    toCSV: function() {
+    toCSV: function(options) {
       var delim = ',', qualifier = '"', escape = '\\', encloseNumbers = true, keys = false;
       var dataArray = [];
 
@@ -454,15 +454,15 @@ string.js - Copyright (C) 2012-2013, JP Richardson <jprichardson@gmail.com>
         return it !== null && it !== '';
       }
 
-      if (typeof arguments[0] === 'object') {
-        delim = arguments[0].delimiter || delim;
-        delim = arguments[0].separator || delim;
-        qualifier = arguments[0].qualifier || qualifier;
-        encloseNumbers = !!arguments[0].encloseNumbers;
-        escape = arguments[0].escape || escape;
-        keys = !!arguments[0].keys;
-      } else if (typeof arguments[0] === 'string') {
-        delim = arguments[0];
+      if (typeof options === 'object') {
+        delim = options.delimiter === undefined ? delim : options.delimiter;
+        delim = options.separator === undefined ? delim : options.separator;
+        qualifier = (options.qualifier === undefined ? qualifier : options.qualifier);
+        escape = (options.escape === undefined ? escape : options.escape);
+        encloseNumbers = !!options.encloseNumbers;
+        keys = !!options.keys;
+      } else if (typeof options === 'string') {
+        delim = options;
       }
 
       if (typeof arguments[1] === 'string')