diff --git a/lib/connect-logger.js b/lib/connect-logger.js
index 16eef50..8162b50 100644
--- a/lib/connect-logger.js
+++ b/lib/connect-logger.js
@@ -1,5 +1,6 @@
 "use strict";
 var levels = require("./levels");
+var _ = require('underscore');
 var DEFAULT_FORMAT = ':remote-addr - -' +
   ' ":method :url HTTP/:http-version"' +
   ' :status :content-length ":referrer"' +
@@ -88,11 +89,12 @@ function getLogger(logger4js, options) {
 					if(res.statusCode >= 400) level = levels.ERROR;
 				}
 				if (thislogger.isLevelEnabled(level)) {
+          var default_tokens = assemble_tokens(req, res);
 					if (typeof fmt === 'function') {
-						var line = fmt(req, res, function(str){ return format(str, req, res); });
+						var line = fmt(req, res, function(str){ return format(str, default_tokens); });
 						if (line) thislogger.log(level, line);
 					} else {
-						thislogger.log(level, format(fmt, req, res));
+						thislogger.log(level, format(fmt, default_tokens));
 					}
 				}
 			});
@@ -103,6 +105,40 @@ function getLogger(logger4js, options) {
   };
 }
 
+/**
+ * Adds custom {token, replacement} objects to defaults, overwriting the defaults if any tokens clash
+ *
+ * @param  {IncomingMessage} req
+ * @param  {ServerResponse} res
+ * @param  {Array} custom_tokens [{ token: string-or-regexp, replacement: string-or-replace-function }]
+ * @return {Array}
+ */
+function assemble_tokens(req, res) {
+  var default_tokens = [];
+  default_tokens.push({ token: ':url', replacement: req.originalUrl });
+  default_tokens.push({ token: ':method', replacement: req.method });
+  default_tokens.push({ token: ':status', replacement: res.__statusCode || res.statusCode });
+  default_tokens.push({ token: ':response-time', replacement: res.responseTime });
+  default_tokens.push({ token: ':date', replacement: new Date().toUTCString() });
+  default_tokens.push({ token: ':referrer', replacement: req.headers.referer || req.headers.referrer || '' });
+  default_tokens.push({ token: ':http-version', replacement: req.httpVersionMajor + '.' + req.httpVersionMinor });
+  default_tokens.push({ token: ':remote-addr', replacement: req.ip || req._remoteAddress ||
+    (req.socket && (req.socket.remoteAddress || (req.socket.socket && req.socket.socket.remoteAddress))) });
+  default_tokens.push({ token: ':user-agent', replacement: req.headers['user-agent'] });
+  default_tokens.push({ token: ':content-length', replacement: (res._headers && res._headers['content-length']) ||
+      (res.__headers && res.__headers['Content-Length']) || '-' });
+  default_tokens.push({ token: /:req\[([^\]]+)\]/g, replacement: function(_, field) {
+    return req.headers[field.toLowerCase()];
+  } });
+  default_tokens.push({ token: /:res\[([^\]]+)\]/g, replacement: function(_, field) {
+    return res._headers ?
+      (res._headers[field.toLowerCase()] || res.__headers[field])
+      : (res.__headers && res.__headers[field]);
+  } });
+
+  return default_tokens;
+};
+
 /**
  * Return formatted log line.
  *
@@ -113,33 +149,10 @@ function getLogger(logger4js, options) {
  * @api private
  */
 
-function format(str, req, res) {
-	return str
-    .replace(':url', req.originalUrl)
-    .replace(':method', req.method)
-    .replace(':status', res.__statusCode || res.statusCode)
-    .replace(':response-time', res.responseTime)
-    .replace(':date', new Date().toUTCString())
-    .replace(':referrer', req.headers.referer || req.headers.referrer || '')
-    .replace(':http-version', req.httpVersionMajor + '.' + req.httpVersionMinor)
-    .replace(
-      ':remote-addr', req.ip || req._remoteAddress || (
-      req.socket &&
-        (req.socket.remoteAddress || (req.socket.socket && req.socket.socket.remoteAddress))
-    ))
-    .replace(':user-agent', req.headers['user-agent'] || '')
-    .replace(
-      ':content-length',
-      (res._headers && res._headers['content-length']) ||
-        (res.__headers && res.__headers['Content-Length']) ||
-        '-'
-    )
-    .replace(/:req\[([^\]]+)\]/g, function(_, field){ return req.headers[field.toLowerCase()]; })
-    .replace(/:res\[([^\]]+)\]/g, function(_, field){
-      return res._headers ?
-        (res._headers[field.toLowerCase()] || res.__headers[field])
-        : (res.__headers && res.__headers[field]);
-    });
+function format(str, tokens) {
+  return _.reduce(tokens, function(current_string, token) {
+    return current_string.replace(token.token, token.replacement);
+  }, str);
 }
 
 /**
diff --git a/package.json b/package.json
index 0a2231e..bf7ba8d 100644
--- a/package.json
+++ b/package.json
@@ -31,7 +31,8 @@
   "dependencies": {
     "async": "~0.2.0",
     "readable-stream": "~1.0.2",
-    "semver": "~1.1.4"
+    "semver": "~1.1.4",
+    "underscore": "1.8.2"
   },
   "devDependencies": {
     "vows": "0.7.0",