diff --git a/colors.js b/colors.js
index 44ee612..96c436f 100644
--- a/colors.js
+++ b/colors.js
@@ -98,7 +98,7 @@ function stylize(str, style) {
       'yellow'    : ['<span style="color:yellow;">',  '</span>']
     };
   } else if (exports.mode === 'none') {
-    return str;
+    return str+'';
   } else {
     console.log('unsupported mode, try "browser", "console" or "none"');
   }
diff --git a/test.js b/test.js
index 1c03d65..d74432a 100644
--- a/test.js
+++ b/test.js
@@ -46,6 +46,11 @@ aE(s, 'red', 31);
 aE(s, 'yellow', 33);
 assert.equal(s, 'string');
 
+colors.setTheme({error:'red'});
+
+assert.equal(typeof("astring".red),'string');
+assert.equal(typeof("astring".error),'string');
+
 colors.mode = 'browser';
 assert.equal(s.bold, '<b>' + s + '</b>');
 assert.equal(s.italic, '<i>' + s + '</i>');
@@ -57,9 +62,14 @@ stylesColors.forEach(function (color) {
   assert.equal(colors[color](s), h(s, color));
 });
 
+assert.equal(typeof("astring".red),'string');
+assert.equal(typeof("astring".error),'string');
+
 colors.mode = 'none';
 stylesAll.forEach(function (style) {
   assert.equal(s[style], s);
   assert.equal(colors[style](s), s);
 });
 
+assert.equal(typeof("astring".red),'string');
+assert.equal(typeof("astring".error),'string');