diff --git a/lib/nopt.js b/lib/nopt.js
index 97e1de9..24855cd 100644
--- a/lib/nopt.js
+++ b/lib/nopt.js
@@ -4,7 +4,8 @@ var debug = process.env.DEBUG_NOPT || process.env.NOPT_DEBUG
   ? function () { console.error.apply(console, arguments) }
   : function () {}
 
-var path = require("path")
+var url = require('url')
+  , path = require("path")
   , Stream = require("stream").Stream
   , abbrev = require("abbrev")
   , os = require("os")
@@ -25,7 +26,7 @@ exports.clean = clean
 exports.typeDefs =
   { String  : { type: String,  validate: validateString  }
   , Boolean : { type: Boolean, validate: validateBoolean }
-  , URL     : { type: URL,     validate: validateUrl     }
+  , url     : { type: url,     validate: validateUrl     }
   , Number  : { type: Number,  validate: validateNumber  }
   , path    : { type: path,    validate: validatePath    }
   , Stream  : { type: Stream,  validate: validateStream  }