diff --git a/colors.js b/colors.js
index 1cf8636..8f1b372 100644
--- a/colors.js
+++ b/colors.js
@@ -50,7 +50,7 @@ var addProperty = function (color, func) {
   };
 
   if (Object.defineProperty) {
-    Object.defineProperty(Object.prototype, color, {
+    Object.defineProperty(String.prototype, color, {
       get : func,
       configurable: true,
       enumerable: false